Disposable LMA

ABSTRACT

The disclosed method for fabricating low cost laryngeal mask devices includes providing a mold, the mold including interior walls that define a hollow interior volume. The interior volume includes a first portion and a second portion. A liquid plastic material is introduced into the mold, and then the mold is moved so as to coat the mold&#39;s interior walls. The liquid plastic material and then allowed to cure. The cured plastic material is then removed from the mold and the cured plastic material includes a generally elliptically shaped plate and a cuff. The cuff is formed from plastic material that coated the portion of the interior walls that defined the first portion. The plate defines a laryngeal side, a pharyngeal side, and a central aperture. An interior perimeter of the cuff is attached to the laryngeal side of the plate proximal to a perimeter of the central aperture. An outer perimeter of the cuff is attached to the laryngeal side of the plate proximal to an outer perimeter of the plate.

This application claims the benefit of provisional application Ser. No.60/128,469 filed Apr. 9, 1999.

BACKGROUND OF THE INVENTION

The present invention relates to a laryngeal mask airway device. Morespecifically, the present invention relates to reduced cost laryngealmasks, improved geometric configurations for laryngeal masks, and tomethods of inexpensively fabricating such masks.

The laryngeal mask airway device (LMA) is a well known device that isuseful for establishing airways in unconscious patients. LMAs have beenin use for about twelve years and offer an alternative to the older,even better known, endotracheal tube. For at least seventy years,endotracheal tubes comprising a long slender tube with an inflatableballoon disposed at the tube's distal end have been used forestablishing airways in unconscious patients. In operation, theendotracheal tube's distal end is inserted through the mouth of thepatient, past the patient's laryngeal inlet (or glottic opening), andinto the patient's trachea. Once so positioned, the balloon is inflatedso as to form a seal with the interior lining of the trachea. After thisseal is established, positive pressure may be applied to the tube'sproximal end to ventilate the patient's lungs. Also, the seal betweenthe balloon and the inner lining of the trachea protects the lungs fromaspiration (e.g., the seal prevents material regurgitated from thestomach from being aspirated into the patient's lungs).

Although they have been enormously successful, endotracheal tubes sufferfrom several major disadvantages. The principal disadvantage of theendotracheal tube relates to the difficulty of properly inserting thetube. Inserting an endotracheal tube into a patient is a procedure thatrequires a high degree of skill. Also, even for skilled practitioners,insertion of an endotracheal tube is sometimes difficult or notpossible. In many instances, the difficulty of inserting endotrachealtubes has tragically led to the death of a patient because it was notpossible to establish an airway in the patient with sufficient rapidity.

In addition to this principal disadvantage, there are also otherdisadvantages associated with endotracheal tubes. For example,intubation with an endotracheal tube often causes patients to sufferfrom severe “sore throats”. The “sore throat” is principally caused byfriction between the tube and the notch between the patient's arytenoidcartilages. Another disadvantage is that patients can not cougheffectively while intubated with an endotracheal tube. Yet anotherproblem with endotracheal tubes relates to the manner in which they areinserted. Inserting an endotracheal tube normally requires manipulationsof the patient's head and neck and further requires the patient's jaw tobe forcibly opened widely. These necessary manipulations make itdifficult, or undesirable, to insert an endotracheal tube into a patientwho may be suffering from a neck injury. Still another disadvantage isthat endotracheal tubes provide an airway that is relatively small ornarrow. The size of the airway must be relatively narrow because thedistal end of the tube must be sufficiently small to fit into thetrachea.

In contrast to the endotracheal tube, it is relatively easy to insert anLMA into a patient and thereby establish an airway. Also, the LMA is a“forgiving” device in that even if it is inserted improperly, it stilltends to establish an airway. Accordingly, the LMA is often thought ofas a “life saving” device. Also, the LMA may be inserted with onlyrelatively minor manipulations of the patient's head, neck, and jaw.Further, the LMA provides for ventilation of the patient's lungs withoutrequiring contact with the sensitive inner lining of the trachea and thesize of the airway established with an LMA is typically significantlylarger than the size of the airway established with an endotrachealtube. Also, the LMA does not interfere with coughing to the same extentas endotracheal tubes. Largely due to these advantages, the LMA hasenjoyed increasing popularity over the last twelve years.

FIG. 1 shows a perspective view of a prior art LMA 100 and FIG. 2illustrates an LMA 100 that has been inserted into a patient. LMAs suchas LMA 100 are described for example in U.S. Pat. No. 4,509,514. LMA 100includes a flexible cylindrical tube 110 and a mask portion 130. Tube110 extends from a proximal end 112 to a distal end 114 and mask portion130 is coupled to the tube's distal end 114. Mask portion 130 includes aproximal end 132 and a generally elliptical inflatable cuff 134. Maskportion 130 also defines a central passageway extending from proximalend 132 to an open end 136 of cuff 134. The distal end 114 of tube 110is telescopically fit into the proximal end 132 of mask portion 130, andLMA 100 provides a continuous, sealed, airway extending from proximalend 112 of tube 110 to the open end 136 of cuff 134. LMA 100 alsoincludes an inflation tube 138 for selectively inflating or deflatingcuff 134.

In operation, the cuff 134 is deflated, and then the mask portion isinserted through the patient's mouth into the patient's pharynx. Themask portion is preferably positioned so that a distal end 140 of cuff134 rests against the patient's normally closed esophagus and so thatthe open end 136 of the cuff 134 is aligned with the entryway of thepatient's trachea (i.e., the patient's glottic opening). After the maskportion is so positioned, the cuff is inflated thereby forming a sealaround the patient's glottic opening and this establishes a sealedairway extending from the proximal end 112 of the tube 110 to thepatient's trachea.

For convenience of exposition, the term “fully inserted configuration”shall be used herein to refer to an LMA that has been inserted into apatient and has the following characteristics: (1) the mask portion isdisposed around the patient's glottic opening; (2) the cuff is inflatedforming a seal around the patient's glottic opening; and (3) the airwaytube extends from a proximal end located outside the patient's mouth toa distal end that is coupled to the mask portion, the tube extendingthrough the patient's mouth and the patient's natural upper airway sothat the LMA provides a sealed airway extending from the tube's proximalend to the patient's lungs. FIG. 2 shows an LMA in the fully insertedconfiguration.

When LMA 100 is in the fully inserted configuration, LMA 100advantageously does not contact the interior lining of the trachea.Rather, the seal is established by contact between the tissuessurrounding the patient's laryngeal inlet and the inflatable cuff 134.Unlike the delicate interior lining of the trachea, the tissues at thelaryngeal inlet are accustomed to contact with foreign matter. Forexample, during the act of swallowing food, the food is normallysqueezed against these tissues on its way to the esophagus. Thesetissues are accordingly less sensitive and less susceptible to beingdamaged by contact with the inflatable cuff.

FIG. 3 shows a sectional side view of the mask portion 230 of anotherprior art LMA. The illustrated mask portion 230, which is described morefully in U.S. Pat. No. 5,355,879, includes an inflatable cuff 234 and abackplate 250. Backplate 250 defines a proximal end 232 for receiving,or coupling to, a cylindrical airway tube (not shown). Mask portion 230defines a sealed passageway, or airway, that extends from proximal end232 through to the open end 236 of cuff 234. This mask portion 230 alsoincludes an inflatable back cushion that, when inflated, expands to thecontour illustrated by phantom outline 252. As shown in FIG. 3, thecross sections of prior art cuffs are generally circular. The thicknessT1 of the material used to form the cuff (i.e., the thickness of thecuff wall) is normally about 0.7-0.8 millimeters.

U.S. Pat. No. 5,303,697 describes an example of another type of priorart LMA that is commonly known as an “intubating LMA”. The intubatingLMA is useful for facilitating insertion of an endotracheal tube. Afteran intubating LMA has been located in the fully inserted configuration,the LMA can act as a guide for a subsequently inserted endotrachealtube. Use of the LMA in this fashion facilitates what is commonly knownas “blind insertion” of the endotracheal tube. Only minor movements ofthe patient's head, neck, and jaw are required to insert the intubatingLMA, and once the intubating LMA has been located in the fully insertedconfiguration, the endotracheal tube may be inserted with virtually noadditional movements of the patient. This stands in contrast to therelatively large motions of the patient's head, neck, and jaw that wouldbe required if the endotracheal tube were inserted without theassistance of the intubating LMA.

U.S. Pat. No. 5,632,271 describes an example of yet another type ofprior art LMA. In addition to providing an airway tube for ventilating apatient's lungs, this LMA also provides a second tube, a drainage tube,used for draining or removing regurgitated material. The distal end ofthe drainage tube is disposed proximal to the normally closed entranceto the patient's esophagus. In addition to providing drainage, thedrainage tube may also be used to guide insertion of a gastric tube.

In general, prior art LMAs have been manufactured by molding elastomericmaterials such as silicone to desired shapes. One advantage of thesematerials is that they are durable enough to permit the LMAs to besterilized in an autoclave and reused. For example, LMAs sold by LMAInternational SA of Henley, England are guaranteed to survive fortysterilizations, and in practice these devices may generally besterilized (and reused) more than forty times before becoming too wornfor reuse. However, one disadvantage of these materials is that they arerelatively expensive. Accordingly, it would be advantageous to develop areduced cost LMA.

Several attempts have been made in the prior art to provide reduced costLMAs. For example, U.S. Pat. No. 6,012,452 discloses an LMA in which themask portion is formed by adhering a foam material to both sides of abackplate. The foam forms an inflatable cuff that is attached to bothsides of the plate. U.S. Pat. No. 5,983,897 discloses another LMA inwhich the mask portion is formed by attaching cuff members to the topand bottom of a backplate. The cuff members may be formed from flexible,resilient plastics material, such as PVC. One disadvantage of the LMAsdisclosed in the '897 and '452 patents is that the assembly of thedisclosed mask portions necessarily involves two steps: a first step offabricating the backplate and then a second step of adhering the cuff tothe top and bottom of the plate. It would therefore be advantageous todevelop a process for simultaneously forming all parts of the maskportion of an LMA.

In addition to cost, another disadvantage of prior art LMAs relates tothe quality of the seal established between the patient and the LMA. TheLMA shown in FIG. 1 generally maintains a seal up to about twenty cmH₂O. That is, when the LMA is in the fully inserted configuration, theseal between the LMA and the patient will be maintained as long as thepressure applied to the proximal end of the airway tube is less thanapproximately twenty cm H₂O. However, if greater pressures are appliedto the proximal end of the airway tube, the seal tends to be lostthereby causing loss of some fraction of the delivered gas volume, sothat positive pressure ventilation may be less effective. This stands incontrast to the endotracheal tube, which can normally maintain a seal upto fifty cm H₂O. Accordingly, it would be advantageous to provide an LMAthat provides improved seals.

Still another disadvantage of prior art LMAs relates to the profile, orgeometric configuration, of the deflated LMA. When the cuff of an LMA isdeflated, the LMA would ideally, automatically, assume a shape that wasoptimized for facilitating insertion. However, prior art LMAs do nottend to automatically form such shapes when the cuff is deflated.Accordingly, several “forming tools” have been provided for affectingthe shape of the deflated LMA. U.S. Pat. No. 5,711,293 discloses onesuch forming tool. However, it would be advantageous to provide an LMAthat automatically assumed a profile that facilitated insertion when thecuff was deflated.

Yet another disadvantage of prior art LMAs relates to the manner inwhich they are inserted into a patient. Anesthesiologists or otherpractitioners insert many types of prior art LMAs by pushing one oftheir fingers against the proximal end of the cuff. Unfortunately, thisprocedure requires the practitioner to insert their finger into thepatient's mouth and guide the LMA past the patient's throat. Since manypractitioners prefer to avoid inserting their fingers into patient'smouths, several insertion tools have been developed for facilitatinginsertion of various LMAs. However, it would be advantageous to providean LMA that could be inserted without an insertion tool and withoutrequiring insertion of a finger into the patient's mouth.

SUMMARY OF THE INVENTION

These and other objects are provided by laryngeal mask airway devicesthat are characterized by improved geometric configurations and bymethods of making such a devices. As will be discussed below, a reducedcost process for making a laryngeal mask airway device according to theinvention includes a process known as rotational molding. The improveddevice includes two principal components: (1) a mask portion and (2) anairway tube. The device is fabricated by attaching the backplate portionof the airway tube to the mask portion. As will be discussed in greaterdetail below, the configuration of the two principal components (1)reduces the cost of fabricating the device and (2) improves theperformance of the device.

Still other objects and advantages of the present invention will becomereadily apparent to those skilled in the art from the following detaileddescription wherein several embodiments are shown and described, simplyby way of illustration of the best mode of the invention. As will berealized, the invention is capable of other and different embodiments,and its several details are capable of modifications in variousrespects, all without departing from the invention. Accordingly, thedrawings and description are to be regarded as illustrative in nature,and not in a restrictive or limiting sense, with the scope of theapplication being indicated in the claims.

BRIEF DESCRIPTION OF THE FIGURES

For a fuller understanding of the nature and objects of the presentinvention, reference should be made to the following detaileddescription taken in connection with the accompanying drawings in whichthe same reference numerals are used to indicate the same or similarparts wherein:

FIG. 1 shows a perspective view of a prior art LMA.

FIG. 2 shows a prior art LMA inserted into a patient in the fullyinserted configuration.

FIG. 3 shows a sectional view of another prior art LMA.

FIG. 4A shows a side view of an LMA constructed according to theinvention, the mask portion of the LMA being in an inflated condition.

FIGS. 4B and 4C show two perspective views of the LMA shown in FIG. 4A.

FIG. 5A shows a side view of the inflated mask portion of the LMA shownin FIGS. 4A, 4B, and 4C.

FIGS. 5B and 5C show two perspective views of the anterior portion ofthe mask portion shown in FIG. 5A.

FIG. 5D shows a perspective view of the posterior portion of the maskportion shown in FIG. 5A.

FIG. 5E shows a posterior view of the mask portion shown in FIG. 5A.

FIG. 6 shows a sectional view of the mask portion taken in the directionof line 6—6 as shown in FIG. 5A.

FIG. 7A shows a side view of the mask portion shown in FIG. 5A when themask portion is deflated.

FIG. 7B shows an anterior view of the deflated mask portion shown inFIG. 7A.

FIG. 8A shows a top view of a mold that may be used to make the maskportion shown in FIG. 5-7.

FIG. 8B shows a sectional view of the mold taken in the direction ofline 8B—8B as shown in FIG. 8A.

FIGS. 8C and 8D show perspective views of the mold shown in FIG. 8A.

FIG. 9A shows a side view of the airway tube of the LMA shown in FIGS.4A, 4B, and 4C.

FIG. 9B shows a perspective view of the proximal section of the airwaytube shown in FIG. 9A.

FIGS. 9C and 9D show views of the proximal section taken in thedirection of lines 9C—9C and 9D—9D, respectively, as shown in FIG. 9B.

FIG. 9E shows a side view of the integral tube and backplate section ofthe airway tube shown in FIG. 9A.

FIGS. 9F and 9G show two perspective views of the integral tube andbackplate section shown in FIG. 9E.

FIG. 10A shows a sectional view of the proximal section inserted intothe integral tube and backplate section taken in the direction of theline 10A—10A as shown in FIG. 9A.

FIG. 10B shows a sectional view of the curved portion of the integraltube and backplate section taken in the direction of line 10B—10B asshown in FIG. 9A.

FIG. 10C shows a sectional view of the same component illustrated inFIG. 10B when that component is subjected to external compressiveforces.

FIG. 10D shows a side view of an embodiment of an intubating LMAconstructed according to the invention, an endotracheal tube extendingthrough the LMA.

FIG. 10E shows a sectional view of the intubating LMA taken along line10E—10E as shown in FIG. 10D.

FIG. 10F shows a side view of another embodiment of an LMA constructedaccording to the invention.

FIG. 10G shows a perspective view of the embodiment shown in FIG. 10F.

FIG. 11 shows a perspective view of a tube that has formed a kink inresponse to bending of the tube.

FIG. 12 shows a perspective view of an LMA constructed according to theinvention in which the inflation tube has been attached to the airwaytube so that the inflation tube extends into one of the grooves in theairway tube.

FIG. 13 illustrates how the airway tube shown in FIG. 9A deviates fromits preformed configuration when the LMA is located in the fullyinserted configuration.

FIG. 14 shows a perspective view of the laryngeal side of the maskportion of an LMA and illustrates the regions of the mask portion thatform seals with different portions of the human anatomy when the LMA islocated in the fully inserted configuration.

FIG. 15A shows a sectional view of a prior art LMA that has been locatedin the fully inserted configuration.

FIG. 15B shows a sectional view of an LMA constructed according to theinvention that has been located in the fully inserted configuration.

FIG. 16A shows a side view of the LMA shown in FIG. 4A when the maskportion is deflated.

FIGS. 16B and 16C show perspective views of the LMA, with deflated maskportion, shown in FIG. 16A.

FIG. 17 shows an LMA constructed according to the invention that ispartially inserted into a patient.

FIG. 18A shows a side view of another LMA constructed according to theinvention.

FIGS. 18B and 18C show perspective views of the LMA shown in FIG. 18A.

FIG. 18D shows a sectional view of the airway tube taken in thedirection of the line 18D—18D as shown in FIG. 18A.

FIG. 19A illustrates how the airway tube of the LMA shown in FIGS.18A-18D can be used to guide a subsequently inserted endotracheal tube.

FIG. 19B shows an alternative embodiment of the LMA shown in FIGS.18A-18C constructed according to the invention in which the proximal endof the plate is not fixed to the proximal end of the backplate portionof the airway tube.

FIG. 20 shows an alternative embodiment of a mask portion constructedaccording to the invention.

FIG. 21 is a simplified view in perspective for another LMA deviceaccording to the invention, as seen in three-quarter perspective andviewing the posterior side of mask structure, in inflated condition atthe distal end of an airway tube.

FIG. 22 is a similar view of the structure of FIG. 21, as seen from theanterior (or trachea-facing) side of the device of FIG. 21, but in theevacuated state wherein thin-film material of the inflation is collapsedand matted against skeletal base structure of the device.

FIG. 23 is a view similar to FIG. 21, for an LMA device having agastric-drainage feature of the invention.

FIG. 24 is a view similar to FIG. 22, for the device of FIG. 23.

FIG. 25 is a sectional view taken generally in the longitudinal sagittalplane of the device of FIG. 23, certain parts being omitted, forclarity.

FIG. 26 is a plan view of the posterior side of the device of FIG. 23,certain parts being omitted for clarity.

FIG. 27 is a plan view as in FIG. 26 but with added showing, to includestructure omitted from FIG. 26.

FIG. 28 is a sectional view, taken at 28—28 in FIG. 27.

FIG. 29 is a similar sectional view, but taken at 29—29 in FIG. 27.

FIG. 30 is a longitudinal section as in FIG. 25, for a modifiedembodiment of the invention.

FIG. 31 is another and similar longitudinal section, taken only to showan integrally formed feature of the invention, being a major componentof the embodiment of FIG. 30.

FIG. 31A is a view similar to FIG. 31 to show a modification.

FIG. 32 is a plan view of the posterior side of the component of FIG.31.

FIG. 33 is a view of a slightly modified version of the component ofFIG. 31.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 4A shows a side view of one embodiment of an LMA 400 constructedaccording to the invention. FIGS. 4B and 4C show two perspective viewsof LMA 400. LMA 400 is preferably constructed from two separate piecesthat are bonded, or adhered, together. The first piece is an airway tube410 and the second piece is a mask portion 430. In FIGS. 4A, 4B, and 4C,the mask portion 430 is shown in an inflated condition. As will bediscussed in greater detail below, mask portion 430 may advantageouslybe formed by a process called rotational molding. The airway tube 410may also be produced by rotational molding, or alternatively, could beproduced using injection or other types of molding.

FIG. 5A shows a side view of mask portion 430 when inflated. FIGS. 5Band 5C show two perspective views of the anterior side of mask portion430 when inflated. FIG. 5D shows a perspective view of the posteriorside of mask portion 430 when inflated, and FIG. 5E shows a view of theposterior side of mask portion 430 when inflated. The terms anterior andposterior as used above in connection with FIGS. 5B-5E are made withreference to the fully inserted configuration. That is, when the LMA 400is in the fully inserted configuration, the portion of the mask portion430 shown in FIGS. 5B and 5C will be located forward of, or anterior to,the portion shown in FIGS. 5D and 5E. Also, when LMA 400 is in the fullyinserted configuration, the portion of mask portion 430 shown in FIGS.5D and 5E will be disposed proximal to the patient's pharyngeal wall,posterior to the portions shown in FIGS. 5B and 5C. FIG. 6 shows asectional view of mask portion 430 taken in the direction of line 6—6 asshown in FIG. 5A. FIGS. 7A and 7B show side and anterior views,respectively, of mask portion 430 when deflated.

Mask portion 430 includes a plate 440, an inflatable cuff 460, and aninflation tube 490. Mask portion 430 also defines a proximal end 432 anda distal end 434 (shown for example in FIG. 5D). Plate 440 ischaracterized by a generally elliptical shape and defines a centralaperture or through hole 442 (shown best in FIG. 5E). For convenience ofexposition, the shape of plate 440 may be referred to as that of anelliptical annulus. A classic annulus has circular symmetry, however,the elliptical annulus of plate 440 follows the elliptical profileillustrated in FIG. 5E. Plate 440 also defines a pharyngeal side 444 anda laryngeal side 446 (shown for example in FIG. 5A). The pharyngeal side444 of plate 440 is so named because, as will be discussed below, thepharyngeal side 444 is disposed proximal to the pharyngeal wall of apatient when LMA 400 is in the fully inserted configuration. The centralaperture 442 of plate 440 extends through the entire plate from thepharyngeal side 444 to the laryngeal side 446. The distance between thepharyngeal side 444 and the Laryngeal side 446 of plate 440, or thethickness of the plate, shall be referred to as T2, as shown in FIG. 6.In some embodiments, the plate is substantially flat in that thethickness T2 is substantially uniform throughout the plate. Onepreferred value for the thickness T2 of the substantially flat plate 440is about two millimeters plus or minus one millimeter. Even morepreferably, the thickness T2 of the substantially flat plate 440 is twomillimeters plus or minus 0.5 millimeters. Even more preferably, thethickness T2 of the substantially flat plate 440 is substantially equalto two millimeters. In other embodiments, it may be advantageous for theplate to have a tapering thickness so that the plate is thicker at theproximal end than at the distal end. For example, the thickness of theplate T2 may be about two millimeters at the proximal end and maysmoothly taper to about one and a half millimeters at the distal end.

Inflatable cuff 460 is formed from a very thin, flexible, sheet ofmaterial that is attached to the laryngeal side 446 of plate 440. Asshown best in FIG. 6, the cross-section of cuff 460, when inflated, isgenerally U-shaped (or has the shape of an inverted “U”). The generallyelliptical inner periphery 460-I of cuff 460 is sealed, or attached, toplate 440 proximal to the generally elliptical periphery of aperture442, and the generally elliptical outer periphery 460-O of cuff 460 issealed, or attached, to plate 440 proximal to the generally ellipticalouter periphery of the plate 440. The thickness of the cuff (i.e., thecuff wall), as shown in FIG. 6, shall be referred to as T3. Onepreferred value for the thickness T3 of the cuff is about 0.04 to 0.24millimeters. More preferably, the thickness T3 is in the range 0.08 to0.20 millimeters (or 0.14 plus or minus 0.06 millimeters). Even morepreferably, the thickness T3 of the cuff is 0.14 plus or minus 0.03millimeters.

For convenience of exposition, the shape of the inflated cuff 460 shallbe referred to as “generally toroidal”. The shape of the cuff is notstrictly a torus for several reasons. For example, the cross section ofthe cuff is U-shaped rather than circular (as shown in FIG. 6). Also, aclassic torus has a ring-like, or doughnut, shape (and is formed byrotating a circle about an axis in the plane of the circle that does notintersect the circle), whereas the cuff 460 follows the generallyelliptical shape of the plate 440. Also, the thickness of the inflatedcuff is not constant from the proximal end to the distal end (as shownfor example in FIG. 5A by the angle alpha). However, despite thesevariations from the classic torus, the inflated cuff may be described ashaving a generally toroidal configuration (since it is essentiallyformed by sweeping the U-shaped cross section of the inflated cuff alongthe elliptical contour defined by the plate 440).

Plate 440 and cuff 460 of mask portion 430 cooperate to define agenerally toroidal interior volume. Inflation tube 490 extends from thepharyngeal side 444 of plate 440 through the plate and into the interiorvolume to permit selective inflation and deflation of cuff 460.

Like plate 440, mask portion 430 defines a pharyngeal side and alaryngeal side. The pharyngeal side of mask portion 430 is coincidentwith the pharyngeal side 444 of plate 440. The laryngeal side 448 ofmask portion 430 is defined by inflatable cuff 460. As shown best inFIGS. 5A and 6, when the cuff 460 is inflated, the laryngeal side 448 ofmask portion 430 is defined by the exterior surface of cuff 460 at theportion of the cuff 460 that is disposed opposite to plate 440, orfurthest from plate 440. When LMA 400 is in the fully insertedconfiguration, the laryngeal side 448 of mask portion 430 is in physicalcontact with the tissues surrounding the patient's laryngeal inlet. Asshown best in FIGS. 5D and 5E, when cuff 460 is inflated, the aperture442 extends entirely through the mask portion so that the mask portion430 defines a passage 442 that extends from the laryngeal side to thepharyngeal side.

For convenience of exposition, three directions shall be defined withrespect to mask portion 430. The arrow PtD shown in FIG. 5A extends in aproximal-to-distal direction. Mask portion 430 extends in theproximal-to-distal direction from the proximal end 432 to the distal end434. It will be appreciated that a distal-to-proximal direction extendsopposite to, or is rotated 180 degrees from, the proximal-to-distaldirection. The arrow LtP shown in FIG. 5A extends in alaryngeal-to-pharyngeal direction. Mask portion 430 extends in thelaryngeal-to-pharyngeal direction from laryngeal side 448 to pharyngealside 444. It will be appreciated that a pharyngeal-to-laryngealdirection extends opposite to, or is rotated 180 degrees from, thelaryngeal-to-pharyngeal direction. (The laryngeal-to-pharyngealdirection could also be referred to as the “antero-posterior”direction.) The arrow LtR shown in FIG. 5E extends in the left-to-rightdirection. It will be appreciated that a right-to-left direction extendsopposite to, or is rotated 180 degrees from, the left-to-rightdirection. These directions are so named because when the LMA 400 isinserted into a patient, the LMA will extend from a left side to a rightside within the patient. These right-to-left and left-to-rightdirections could also be referred to as “lateral” directions. Theproximal-to-distal, laryngeal-to-pharyngeal, and left-to-rightdirections are mutually orthogonal and provide a convenient referencecoordinate system for describing the LMA.

As shown in FIG. 5A, the thickness of the inflated mask portion at thedistal end 434 (i.e., the distance between the pharyngeal side 444 andthe laryngeal side 448 of mask portion 430 as measured in thelaryngeal-to-pharyngeal direction) shall be referred to as T4, and thethickness of the inflated mask portion at the proximal end 432, asmeasured in the laryngeal-to-pharyngeal direction, shall be referred toas T5. Preferred values for T4 and T5 in female adult sizes are about12.7 and 25.4 millimeters, respectively. (It will be appreciated thatexternal dimensions such as T4 and T5 would be about thirteen percentlarger in an adult male size of the LMA. Unless otherwise stated,dimensions discussed herein will be for the female adult size.) Theprofile of cuff 460 is preferably smoothly tapered as shown in FIG. 5Aso that the thickness of the mask portion 430 smoothly decreases fromthe proximal end 432 to the distal end 434. This tapering can bedescribed in terms of the angle alpha between the pharyngeal side 444and the laryngeal side 448 of mask portion 430, as shown in FIG. 5A. Onepreferred value for the angle alpha is about ten degrees plus or minusone degree. More preferably, the angle alpha is ten degrees plus orminus half a degree. Most preferably, the angle alpha is substantiallyequal to ten degrees. As will be discussed below, this angle alpha isselected to match the human anatomy to allow all portions of theinflated cuff to contact the tissues surrounding the laryngeal inlet andto thereby provide improved seals.

The plate 440 shown in FIG. 5A is characterized by a substantiallyconstant thickness. That is, the thickness T2 (as shown in FIG. 6) ofplate 440 is substantially constant from the proximal end of the maskportion to the distal end of the mask portion and the variation in themask portion's thickness is entirely provided by the cuff 460. However,as mentioned above, in some embodiments, it may be advantageous toprovide plate 440 with a tapering thickness so that the distal end ofthe plate is thinner than the proximal end.

As shown in FIG. 5E, the length of the plate 440, or the distancebetween the proximal end 432 and the distal end 434 as measured in theproximal-to-distal direction, shall be referred to as L1, and the lengthof aperture 442 as measured in the proximal-to-distal direction shall bereferred to as L2. The width of the plate 440, as measured in theleft-to-right direction, shall be referred to as W1, and the width ofthe aperture 442 as measured in the left-to-right direction shall bereferred to as W2. In adult sizes of LMA 400, preferred values for L1,L2, W1, and W2, are 90, 59, 47, and 26 millimeters, respectively.

As stated above, mask portion 430 may be formed by a process calledrotational molding. FIG. 8A shows a top view of a mold 800 that may beused to produce mask portion 430 by rotational molding. FIG. 8B shows asectional view of mold 800 taken along the line 8B—8B as indicated inFIG. 8A. FIGS. 8C and 8D show perspective views of mold 800. As shown inFIG. 8A, the mold 800 is symmetric about an axis 802. As shown best inFIGS. 8C and 8D, mold 800 includes a top piece 810 and a bottom piece812. When the top piece 810 and bottom piece 812 are bolted or clampedtogether, they cooperatively define a hollow interior volume 820 asshown in FIG. 8B. Interior walls 830 of the mold 800 define theboundaries of hollow interior volume 820.

One portion 822 of the interior volume 820 has a generally toroidalshape corresponding to the generally toroidal shape of the inflated cuff460. Another portion 824 of the interior volume 820 has a generallyelliptical shape corresponding to the shape of plate 440. That is,portion 824 defines a hollow volume, the shape of which is substantiallyidentical to the flat, elliptical shape of plate 440. Similarly, theportion 822 defines a hollow volume, the shape of which is substantiallyidentical to the shape of the inflated cuff 460.

In operation, mask portion 430 may be formed by adding or injecting aliquid plastic material (e.g., polyvinyl chloride or “PVC”) into theinterior volume 820 of mold 800 and by then rotating or otherwise movingmold 800 so as to coat the interior walls 830 with the liquid plasticmaterial. Preferably, the mold 800 is simultaneously rotated about twoaxes that are at ninety degrees to each other (e.g., axis 802 andanother axis that is perpendicular to axis 802). While the mold 800 isrotating, centrifugal forces cause the liquid plastic material to coatall portions of the interior walls 830 of mold 800. After all portionsof the interior walls 830 have been so coated, the mold is thenpreferably held stationary in the position illustrated in FIG. 8B. Thatis, the mold 800 is preferably oriented so that the portion 824 of thehollow interior 820 is at the bottom of the mold (i.e., so that portion824 is parallel to the ground and is closer to the ground, or lower,than any other portion of the hollow interior 820) while the mold 800 isheld stationary. While the mold 800 is held in this stationary position,most of the liquid plastic material drains, or flows, down along theinterior walls 830 into the portion 824. However, all of the liquidplastic material does not flow into portion 824. Rather, surface tensionor other forces cause a thin coating of the liquid plastic material toremain in contact with the interior walls 830 that define the portion822. The mold 800 is preferably held stationary long enough for theplastic material to cure and solidify before the mold is opened byseparating the top and bottom pieces 810, 812.

The material that filled portion 824 forms the plate 440 of the maskportion 430. The thin coating of plastic material that lined theinterior walls 830 of portion 822 forms a cuff 460 that is integrallyattached to the plate 440. Air trapped within the interior volume 820while the mask portion 430 is being formed becomes trapped within thecuff 460. So, when the mask portion 430 is removed from mold 800, thecuff 460 is partially inflated. The cuff 460 is only partially inflated(rather than fully inflated) when the mask portion 430 is removed frommold 800 because, as the mold cools, the trapped air shrinks in volumeand accordingly only partially fills the interior volume defined by thecuff 460.

It will be appreciated that a variety of materials may be introducedinto the mold 800 and used to form mask portion 430. The term liquidplastic material is used herein to refers to any material that iscapable of curing from a liquid or fluid state to a solid, flexible orplastic, state. Due to its flexibility, resistance to stretching, andability to define complex shapes such as that of inflated cuff 460,polyvinyl chloride is a preferred material to use as the liquid plasticmaterial that forms mask portion 430. However, it will be appreciatedthat other materials could also be used.

Once the mold 800 has been opened and the cured plastic plate and cuffhave been removed, fabrication of mask portion 430 may be completed byadding inflation tube 490. It will be appreciated that adding inflationtube 490 is a relatively simple step and is accomplished by forming anaperture in plate 440 that extends from the pharyngeal side 444 throughthe plate and into the interior volume defined by cuff 460, and thenfixing inflation tube 490 to that aperture. Alternatively, as will bediscussed below, it may sometimes be advantageous to provide a maskportion 430 that does not include an inflation tube. In these cases,fabrication of the mask portion is complete as soon as the cured,integrally formed, plate 440 and cuff 460 have been removed from themold 800.

The cured mask portion is preferably relatively soft and flexible. Inone preferred embodiment, the durometer of the cured mask portion 430 isfifty four plus or minus ten on the Shore A scale of hardness. Morepreferably, the durometer of the cured mask portion 430 is fifty fourplus or minus five on the Shore A scale of hardness. Most preferably,the durometer of the cured mask portion 430 is substantially equal tofifty four on the Shore A scale of hardness.

FIG. 9A shows a side view of airway tube 410, which includes a connectorsection 411 and an integral tube and backplate section 416. FIG. 9Bshows a perspective view of connector section 411. FIGS. 9C and 9D showviews of connector section 411 taken in the directions indicated bylines 9C—9C and 9D—9D, respectively, as shown in FIG. 9B. FIG. 9E showsa side view of integral tube and backplate section 416. FIGS. 9F and 9Gshow two perspective views of integral tube and backplate section 416.

Referring to FIGS. 9B, 9C, and 9D, connector section 411 includes aproximal portion 412 and a distal portion 413. Proximal portion 412 ispreferably cylindrical and configured to couple to standard medicalventilating, or anaesthetic devices. Distal portion 413 is preferablyoblong as shown best in the perspective view of FIG. 9B. Connectorsection 411 further includes a disk shaped plate, or flange, 414 thatextends around the junction of proximal portion 412 and distal portion413. Connector section 411 also defines a sealed internal airway passage415 that extends entirely through the proximal portion 412 and thedistal portion 413. In the proximal portion 412, the cross section ofthe passage 415 is circular, and in the distal portion 413, the crosssection of the passage 415 is oblong.

Referring to FIGS. 9E, 9F, and 9G, integral airway tube and backplatesection 416 includes a proximal portion 417, a central or curved portion418, and a backplate portion 419. A disk shaped plate, or flange, 420 isintegrally attached to the proximal end of proximal portion 417. Section416 defines a hollow internal passage 421 that extends entirely throughthe proximal, curved, and backplate portions 417, 418, 419.

Airway tube 410 is assembled by coupling the connector section 411 andthe integral airway tube and backplate section 416 together. As shown inFIG. 9A, when the parts are so coupled, the flange 414 of connectorsection 411 abuts the flange 420 of section 416. Also, the distalportion 413 of connector section 411 extends telescopically into theportion of internal passage 421 that is defined by proximal portion 417of section 416. Also, the internal passage 415 of connector section 411communicates with the internal passage 421 of section 416 so that theairway tube 410 defines a continuous sealed internal passage 424 (shownfor example in FIGS. 10A and 10B) that extends from the tube's proximalend to the tube's distal end. Airway tube 410 also defines a left side410-l, a right side 410-r (shown for example in FIG. 9F), an inner side410-i, and an outer side 410-o (shown for example in FIG. 9E). Note thatthe left and right sides are defined with respect to a person (e.g., aphysician) that is inserting the LMA into a patient and that the leftside 410-l of the tube will actually be disposed on the right side ofthe patient's natural airway when the LMA is in the fully insertedconfiguration.

Backplate portion 419 defines a laryngeal side 422 and a pharyngeal side423. When the LMA 400 is assembled, the laryngeal side 422 of backplateportion 419 is attached or fixed to the pharyngeal side 444 of maskportion 430. Also, when the assembled LMA 400 is in the fully insertedconfiguration, the pharyngeal side 423 of the backplate portion 419contacts the pharyngeal wall of the patient. When LMA 400 is assembled,the internal passage 424 of tube 410 communicates with the passagedefined by mask portion 430 and the LMA 400 defines a sealed airwaypassage that extends from the proximal end of the tube 410 to thecentral aperture 442 of mask portion 430.

The airway tube 410 is sized so that when the LMA is in the fullyinserted configuration, the proximal portion 417 of the airway tube willbe disposed between the patient's upper and lower teeth. FIG. 10A showsa cross-sectional view of the proximal section 417 into which theconnector section 411 has been inserted taken along the line 10A—10A asshown in FIG. 9A. The airway tube 410 is also sized so that when the LMAin the fully inserted configuration, the central portion 418 will extendthrough the patient's natural upper airway between the laryngeal inletand the patient's teeth. FIG. 10B shows a cross sectional view of thecentral portion 418 taken along the line 10B—10B as shown in FIG. 9A. Asshown in FIG. 10B (as well as FIGS. 9A and 9E), airway tube 410 defineslongitudinal folds 425 that extend along the left and right sides of thecentral and backplate portions 418, 419.

Connector section 411 and integral tube and backplate section 416 ofairway tube 410 are preferably formed using molding techniques such asinjection or rotational molding. In one preferred embodiment, connectorsection 411 is formed from polycarbonate and the material of section 411is characterized by a durometer of 95 Shore A. Integral tube andbackplate section 416 is preferably formed from a flexible plasticmaterial (e.g., PVC) and is characterized by a durometer of 70 plus orminus 15 Shore A. More preferably, the material of integral tube andbackplate section 416 is characterized by a durometer of 70 plus orminus 7 (or plus or minus ten percent) Shore A. Still more preferably,the material of integral tube and backplate section 416 is characterizedby a durometer of 70 plus or minus 3.5 (or plus or minus 5 percent)Shore A. Most preferably, the material of integral tube and backplatesection 416 is characterized by a durometer that is substantially equalto 70 Shore A.

Connector section 411 is preferably relatively hard so that (1) it iseasy to reliably attach the proximal portion 412 of section 411 tostandard breathing apparatus and (2) patient's can bite down on thedistal portion 413 without causing collapse or shrinkage of the internalairway passage provided by section 411. Note that when the LMA is in thefully inserted configuration, the patient's teeth will contact proximalportion 417 of the integral tube and backplate section rather thansection 411, because the distal portion of section 411 extends into theproximal portion 417 as illustrated in FIG. 9A. However, pressureapplied by the patient's teeth will be transferred to section 411, andsection 411 is preferably sufficiently hard to resist this pressurewithout allowing the internal passage 415 to collapse.

Section 416 is preferably softer than section 411 to facilitate bendingthe section 416 as necessary to insert the LMA into a patient and topermit unhindered flexion and extension of the patient's neck while LMA400 is in the fully inserted configuration. However, as will bediscussed below, section 416 is preferably stiff enough, at least atroom temperature, so that LMAs constructed according to the inventionmay be inserted by applying pressure to section 416 without requiringinsertion of a finger into the patient's mouth.

Returning to FIGS. 4A-4C, it can be seen that LMA 400 may be formed byfixing or attaching the airway tube 410 to the mask portion 430. Morespecifically, the laryngeal side of the backplate portion of the airwaytube is attached to the pharyngeal side of the mask portion so that theouter perimeter of the laryngeal side 422 of the backplate portionsurrounds the central aperture 442 of the plate 440. The airway tube 410may be attached to the mask portion 430 by heat sealing, gluing, orotherwise bonding or fixing the two components together.

As shown for example in FIG. 9F, the backplate portion 419 defines a“dome shaped” or “bowl shaped” interior volume. When the backplateportion 419 is attached to the mask portion 430, the backplate portion419 and mask portion 430 cooperatively define a hollow bowl shapedinterior volume as shown for example in FIG. 4C. As will be discussedbelow, portions of the larynx extend into this bowl shaped volume whenthe LMA is in the fully inserted configuration.

One advantage of LMA 400 is that it is relatively simple and inexpensiveto produce. As discussed above, both the mask portion 430 and the airwaytube 410 may be produced using a rotational molding process. The airwaytube 410 may alternatively be produced using injection molding. Each ofthese steps (i.e., producing the mask portion 430 and producing theairway tube 410) is relatively simple and inexpensive. Fabrication ofthe LMA 400 may be completed by adding an inflation tube to mask portion430 (in embodiments that use inflation tubes) and by attaching theairway tube 410 to the mask portion 430. Accordingly, LMAs 400 may befabricated at very low cost. This low cost of fabrication enables LMAsconstructed according to the invention to be used as disposable devices.That is, the economics of constructing LMAs according to the invention,such as LMA 400, enable them to be used once and then discarded.

Several structural advantages of LMAs constructed according to theinvention will now be discussed. As shown for example in FIGS. 4A-4C and9A, the backplate portion 419 essentially forms a backplate of the LMA400. In most prior art LMA constructions (e.g., as shown in FIG. 3), themask portion includes a backplate and defines a cylindrical aperture forreceiving, or connecting with, a cylindrical airway tube. Forming themask portion with an added backplate disadvantageously increases (1) themechanical complexity of the mask portion and (2) the cost offabricating the mask portion. Also, the junction, which is found inprior art LMAs, of a cylindrical airway tube and a cylindrical aperturein a backplate tends to form a relatively stiff construction. Forexample, in the LMA illustrated in FIG. 3, it is relatively difficult tocompress the junction of the cylindrical airway tube and the backplatein the direction indicated by arrows 260. Accordingly, this portion ofprior art LMA constructions disadvantageously forms a relatively thick,incompressible, structure that must be pushed between the patient'supper and lower teeth and past the patient's throat to insert the LMA.In contrast to those prior art constructions, the mask portions of LMAsconstructed according to the invention are formed without backplates(e.g., as shown in mask portion 430 in FIGS. 5A-5D) and the backplate ofthe LMA is provided by the airway tube. It is less complex, and lessexpensive, to provide the backplate as part of the airway tube. Also,eliminating the telescopic junction of two cylindrical components thatcharacterized the prior art make LMAs constructed according to theinvention more compressible and easier to insert into patients. Forexample, referring to FIG. 4A, the backplate of LMA 400 compresses inthe direction indicated by arrows 260 more easily than prior art LMAs.This facilitates pushing LMAs constructed according to the inventionbetween the patient's upper and lower teeth and past the patient'sthroat.

In addition to providing a backplate, the general shape of the airwaytube 410 distinguishes LMA 400 from prior art LMAs. In most prior artLMAs (e.g., as shown in FIGS. 1 and 3), the airway tube is cylindrical.While cylindrical airway tubes have functioned well for many years inmany different models of LMAs, the cylindrical configuration has somedisadvantages. One critical feature for an airway tube of any LMA is thesize of the internal airway passage. This passage must be large enoughto provide adequate ventilation of the patient's lungs. That is,moderate pressure differentials (e.g., a pressure drop of one to two cmH₂O) between the proximal and distal ends of the airway tube should besufficient for moving a volume of air through the tube that issufficiently large for adequately ventilating the patient's lungs. Witha cylindrical airway tube it is easy to calculate the volume of air thatcan be moved through the tube for any given pressure differential, andthe volume can be adjusted simply by adjusting (i.e., increasing ordecreasing) the radius of the internal airway passage.

However, one constraint that should be considered in the design ofairway tubes is that these tubes will extend through the patient'smouth, between the patient's upper and lower teeth, for as long as theLMA remains in the fully inserted configuration. So, while an LMA isinserted into a patient, the patient's mouth must remain opened wideenough to create an inter-dental gap (i.e., space between the upper andlower teeth) that is big enough to accommodate the airway tube. Holdingthe mouth open for long periods of time so as to create a largeinter-dental gap can cause discomfort to the patient post operatively.More importantly, some patients cannot open their mouths wide enough topermit easy insertion of adequate sized cylindrical tubes. Accordingly,one disadvantage of cylindrical airway tubes is that they require alarger inter-dental gap than would a tube that had a flatter, or moreoblong, cross section.

Another constraint that should be considered in the design of airwaytubes is that these tubes will extend through the patient's naturalupper airway for as long as the LMA remains in the fully insertedconfiguration. This natural, or anatomical, upper airway, which isformed by several anatomical structures including the pharyngeal wall,hard and soft palates, and tongue, is not itself cylindrical.Accordingly, a cylindrical airway tube does not form a “good fit” withthe anatomical upper airway. For example, when a cylindrical tube isextended through the anatomical upper airway, the tube tends to onlycontact isolated portions of the anatomical structures that define theanatomical upper airway. Accordingly, more pressure is applied to thosestructures, and those structures are subjected to more trauma, thanwould be the case if the shape of the tube better matched the shape ofthe anatomical upper airway.

As shown in FIGS. 9A, 9E, 9F, and 9G, the proximal and central portions417, 418 of the airway tube 410 are oblong or flattened rather thancylindrical. As will be discussed in greater detail below, thisadvantageously (1) maximizes the size of the tube's internal airwaypassage; (2) minimizes the intra-dental gap required for accommodatingthe airway tube; and (3) allows the tube to fit well within, or match,the patient's natural airway.

As stated above, the airway tube 410 is sized so that the proximalsection 417 will be disposed between the patient's upper and lower teethwhen the LMA is in the fully inserted configuration. As shown in FIG.10A, the inter-dental gap G required to accommodate proximal section 417is narrower than would be required if the proximal section 417 werecylindrical. Rather than a circular cross section, the cross section ofthe internal airway passage 424 is oblong. In one preferred embodiment,the thickness G of the proximal section 417 is about 13.0 millimeters.The cross-sectional area of the internal passage defined by airway tube410 is preferably at least as large as that of a cylindrical tube with anine millimeter internal diameter passage. As shown in FIG. 10A, thewidth of the internal passage 424 may be referred to as W3 and thethickness of the internal passage 424 may be referred to as T6. In onepreferred embodiment, W3 and T6 are 20.0 and 6.7 millimeters,respectively.

As also stated above, the airway tube 410 is sized so that the centralportion 418 will extend through the patient's anatomical upper airwaywhile the LMA is in the fully inserted configuration. As shown in FIG.10B, the cross-section of the central portion 418 is oblong rather thancylindrical. Accordingly, the central portion 418 provides a “betterfit” to the anatomical airway than do cylindrical tubes. As shown inFIG. 10B, the width of the central portion of the airway tube may bereferred to as W4 and the thickness of the central portion of the airwaytube may be referred to as T7. One preferred value for W4 is 23.7millimeters plus or minus 10 percent (or plus or minus 2.37 millimeters)and one preferred value for T7 is 10.3 millimeters plus or minus 10percent (or plus or minus 1.03 millimeters). More preferably, W4 and T7are equal to 23.7 millimeters plus or minus 5 percent and 10.3millimeters plus or minus 5 percent, respectively. Even more preferably,W4 and T7 are substantially equal to 23.7 millimeters and 10.3millimeters, respectively. Also, the width W4 of the central portion ofthe airway tube is preferably equal to the thickness T7 times a factorof two, plus or minus ten percent (i.e., W4=(2±0.2)·T7). Morepreferably, the width W4 is equal to the thickness T7 times a factor oftwo, plus or minus five percent (i.e., W4=(2±0.1)·T7).

As shown in FIG. 2, the airway tube of any LMA must follow a curve(about an axis extending in the left-to-right direction) from the pointwhere it couples to the mask portion to the point where the patient'steeth contact the tube. This curve enables the tube to extend throughthe patient's natural upper airway from the teeth to the laryngealinlet. One important design consideration for an airway tube of any LMAis that the airway tube should be designed so that it does not form“kinks” when it is bent, or curved, as necessary for inserting the LMAinto a patient.

FIG. 11 shows an example of a tube that has formed a kink 1102 as aresult of bending the tube by an extreme amount. As is well known, thesize of the internal passageway defined by any tube is dramaticallydecreased at any such kinks 1102. The effects of kinks in tubes iscommonly experienced in connection with garden hoses. For example,formation of a single kink in a garden hose can dramatically decreasethe amount of water that can pass through the hose and be distributed bya sprinkler. The effects of kinks are similar in LMAs. Any kinks formingin the airway tube of an LMA essentially close off the tube's airwaypassage and dramatically decrease the volume of air that can passthrough the tube. Accordingly, it is very important to design the airwaytube so that kinks in the tube do not form when the tube is insertedinto a patient.

One advantage of cylindrical airway tubes over tubes with flatter, ormore oblong, cross sections is that for any given amount of bend, thecylindrical tube is less likely to form a kink. To reduce the risk thatairway tube 410 forms any kinks, tube 410 is preferably provided withtwo longitudinal folds 425 that extend along the left and right sides ofthe tube's central and backplate portions 418, 419. As shown in FIG.10B, the cross-section of the longitudinal fold 425 that extends alongthe left side of the airway tube defines a recess, or groove 425-g thatextends from the left exterior edge of the airway tube towards thecenter of the tube in the left-to-right direction. Similarly, thecross-section of the fold 425 that extends along the right side of theairway tube defines a recess that extends from the right exterior edgeof the airway tube towards the center of the tube in the right-to-leftdirection. Each of the recesses defines an upper exterior surface 425-uand a lower exterior surface 425-l. The thickness of the longitudinalfolds 425 (i.e., the thickness as measured in a direction extending fromthe inner side 410-i to the outer side 410-o of the airway tube) may bereferred to as T12 and the thickness of the longitudinal folds 425 asmeasured in the left-to-right direction may be referred to as T13. Inone preferred embodiment, the thickness T12 and T13 are about threemillimeters and 2.7 millimeters, respectively.

As indicated in FIG. 10B, bending of the tube 410 (about an axisextending in the left-to-right direction) caused by inserting the LMAthrough the patient's anatomical airway generates compressive forces inthe directions indicated by arrows 260. The longitudinal folds 425 tendto prevent localized collapse of the internal passage 424 as a result ofbending the tube. If the tube 410 is subjected to compressive forces inthe direction of arrows 260 sufficiently large to deform the tube, thetube may deform to the shape illustrated in FIG. 10C. As shown, thedeformation of the tube in the region of the longitudinal folds 425 maybe likened to the movement of an accordion or concertina. The size ofthe internal passage 424 does decrease as the tube compresses from theprofile shown in FIG. 10B to the profile shown in FIG. 10C. However,once the airway tube has reached the configuration shown in FIG. 10C,the longitudinal folds 425 resist additional decreases in the size ofthe passage 424, even in response to additional compression of the tube.So, airway tube 410 advantageously (1) reduces the size of theinter-dental gap required for accommodating the tube; (2) provides alarge airway passage; (3) decreases the likelihood that the tube willform kinks when the LMA is inserted into a patient; (4) decreases thelikelihood that the tube will form kinks in response to bending of thepatient's neck over the likely range of head movement; and (5) fits wellwithin the patient's anatomical airway.

Another advantage of the longitudinal folds 425 is that they provide aconvenient groove 425-g for locating the inflation tube 490. FIG. 12shows a perspective view of an LMA 400 constructed according to theinvention in which the inflation tube 490 has been glued into the groove425-g that extends along the right side of the airway tube.

Another important feature of the airway tube 410 is the degree ofcurvature through which the central portion 418 extends. As discussed inU.S. patent application Ser. No. 08/901,055, there is an optimum degreeof curvature for the airway tube of an LMA that will allow the patientto remain in a “neutral position” while the LMA is in the fully insertedconfiguration. The neutral position is a position in which the patientis lying on their back and in which the patient's head is positioned,for example with a pillow, so that the geometric relation of the head tothe rest of the body is the same as when the patient is standing uprightand looking forward. The LMA disclosed in the '055 application used arigid airway tube, and as discussed in that application, for rigidairway tubes the optimum degree of curvature is between 125 and 135degrees. This degree of curvature permits the patient to remain in theneutral position while the LMA is being inserted and after the LMA hasbeen placed in the fully inserted configuration.

For convenience of exposition, the shape assumed by airway tube 410 whenthe tube is not subjected to any external forces shall be referred to asthe “preformed configuration”. As will be discussed below, since theairway tube 410 is somewhat flexible, it can deviate from the preformedconfiguration when the LMA is in use. FIG. 9E shows the integral tubeand backplate section 416 in its preformed configuration. As shown, theairway tube 410 is preferably manufactured so that when it is notsubjected to any external forces, the central portion 418 follows acircular curve about an axis C (the axis C extending in theleft-to-right direction and being perpendicular to the plane of the pagein FIG. 9E) from a proximal limit of curvature 426 to a distal limit ofcurvature 427. In one preferred embodiment, the angle theta between tworays extending from the axis C to the proximal and distal limits 426,427 for the preformed configuration is 105 degrees plus or minus tendegrees. More preferably, the angle theta for the preformedconfiguration is 105 degrees plus or minus five degrees. Even morepreferably, the angle theta is substantially equal to 105 degrees. Inone preferred embodiment of an adult female size, the distance, orradius, R₁, between the axis C and the inner surface 410-i of airwaytube 410 for the preformed configuration is substantially equal to fortymillimeters plus or minus about three millimeters, and the distance, orradius, R₂, between the axis C and the outer surface 410-o of airwaytube 410 for the preformed configuration is substantially equal to fiftymillimeters plus or minus about three millimeters.

The preferred degree of curvature for the preformed configuration of LMA400 is different than for the rigid tube LMA disclosed in theabove-referenced '055 application. This difference in curvaturefacilitates insertion of LMA 400. When an LMA is inserted into apatient, proper insertion begins by placing the mask portion into thepatient's mouth so that the pharyngeal side of the mask is in contactwith the patient's hard palate. At this point, in LMA's designedaccording to the '055 application, the curve in the rigid airway tubeforces the proximal end of the airway tube to be pushed against thepatient's chest. Positioning the end of the tube against the patient'schest makes inserting the LMA somewhat more difficult than if theproximal end could be positioned at a location that was spaced apartfrom the patient's body. However, the requirements of a rigid airwaytube (which facilitates later insertion of an endotracheal tube) andallowing the patient to remain in a neutral position before, during, andafter insertion, necessitates positioning the airway tube's proximal endagainst the patient's chest at the beginning of insertion.

Like the LMA of the '055 application, LMA 400 allows the patient toremain in a neutral position before, during, and after insertion.However, unlike the LMA of the '055 application, the proximal end of theairway tube of LMA 400 need not be positioned against the patient's bodyat any time during insertion. If the airway tube 410 of LMA 400 wererigid and were formed with the above-discussed preformed configuration,then the patient could not remain in a neutral position while the LMAwas in the fully inserted configuration. Rather, the patient's headwould have to be tilted backwards to allow the airway tube to fit intothe patient's anatomical airway. However, since the airway tube 410 isnot rigid, the tube can flex, or bend, slightly away from the preformedconfiguration as it is being inserted thereby allowing the tube to fitinto the anatomical airway of a patient that is in the neutral position.The curve of the preformed configuration of the central portion 418 ofthe airway tube preferably does not deviate far from the anatomicalcurve of 125 to 135 degrees so that the tube need not bend much to fitinto the anatomical airway. However, the curve of the preformedconfiguration of the central portion 418 preferably deviates somewhatfrom the anatomical curve of 125 to 135 degrees so as to eliminate theneed for pressing the tube's proximal end against the patient's chestduring insertion.

FIG. 13 shows in solid lines a side view of integral tube and backplatesection 416 in the preformed configuration. FIG. 13 also shows in dottedlines the shape that integral tube and backplate section 416 assumesafter the LMA 400 has been located in the fully inserted configurationwithin a patient that is resting in the neutral position. As shown, theairway tube 410 bends about an axis extending in the left-to-rightdirection when the LMA is inserted into a patient. When the LMA isinserted into a patient, the center or curvature, or axis about whichthe tube bends, shifts from C to C′, and the angle through which thetube bends changes from the 105 degrees (plus or minus five or tendegrees) of the preformed configuration to the 125 to 135 degreesrequired to fit within the anatomical airway of a patient lying in theneutral position.

As discussed above, in one preferred embodiment, the integral airwaytube and backplate section 416 is formed from polyvinyl chloride. Thismaterial is relatively stiff at room temperature but becomes much moreflexible at body temperature. So, the airway tube is relatively stiff asthe LMA 400 is being inserted into the patient. However, after the LMA400 has been placed in the fully inserted configuration for a while(e.g., three to five minutes), the airway tube softens and becomes morepliable so that its shape easily accommodates to the shape of thepatient's anatomical airway without placing undue force against theanatomical structures that define the anatomical airway. Also, since thematerial is relatively stiff at room temperature, the airway tube isgenerally stiff enough to act as an insertion tool. That is, LMA 400 maybe entirely controlled during insertion simply by manipulating theportions of the airway tube 410 that extend outside of the patient'smouth. This eliminates the need for inserting a finger into thepatient's mouth while inserting the LMA and further eliminates the needfor additional insertion tools.

Another important advantage of LMA 400 relates to the quality of theseal provided with the laryngeal inlet. As shown in FIG. 4A, there is arelatively large empty space S behind the mask portion 430. The emptyspace behind mask portion 430 is substantially larger than that providedby prior art LMAs and, as will be discussed below, advantageously allowsLMA 400 to provide improved seals.

As shown in FIG. 4A, the space S is defined by the distance T9 betweenthe laryngeal side of the proximal end of the inflated cuff and theairway tube 410 as measured in the laryngeal-to-pharyngeal direction. Apreferred value for the distance T9, when the airway tube is in thepreformed configuration, is 32 millimeters plus or minus 3 millimeters.More preferably, the distance T9, when the airway tube is in thepreformed configuration, is 32 millimeters plus or minus 2 millimeters.Even more preferably, the distance T9, when the airway tube is in thepreformed configuration, is substantially equal to 32 millimeters.

When LMA 400 is in the fully inserted configuration, the posteriorportion of the patient's tongue rests in the space S. As will bediscussed below, enlarging the space S in which the tongue restsimproves the quality of the seal between the proximal end of theinflated cuff and the patient's laryngeal inlet.

FIG. 14 shows a view of an inflated cuff of an LMA, and the illustratedcuff has been divided into three different regions. When the LMA islocated in the fully inserted configuration, each region of the cuffcontacts a different portion of the patient's anatomy. Region 1, at thecuff's proximal end, fits into the patient's valleculae (i.e., the spacebehind the lower part of the tongue). Region 2, which is disposedbetween the cuff's proximal and distal ends, contacts the patient'spyriform fossae, which are symmetrically disposed on either side of thepatient's glottic opening. Region 3, which is disposed at the cuff'sdistal end, contacts the patient's cricoid cartilage. Accordingly, whenthe LMA is inserted into a patient, a seal that extends continuouslyaround the patient's glottic opening is formed by contact between theinflated cuff and the patient's valleculae, pyriform fossae, and cricoidcartilage.

FIG. 15A shows a prior art LMA 1500 that has been placed in the fullyinserted configuration. As shown, the inflated cuff 1502 has formed aseal around the patient's glottic opening thereby coupling the passageof the airway tube 1504 to the patient's trachea 1506. The laryngealside of the proximal portion of the cuff fits into the patient'svalleculae 1508, and the laryngeal side of the distal portion of thecuff contacts the patient's cricoid cartilage 1510. The patient's tongue1512 is disposed generally along the inner, or anterior, side of theairway tube between the patient's teeth and the proximal end of theinflated cuff. The posterior portion 1514 of the patient's tongue 1512is disposed in the space S (between the proximal end of the inflatedcuff and the inner, or anterior, side of the airway tube). The dashedline 1516 illustrates the contour the tongue 1512 would follow if theLMA 1500 were not inserted into the patient. As shown, insertion of theLMA displaces the tongue 1512 in the pharyngeal-to-laryngeal directionaway from the natural position indicated by dashed line 1516. Pushingthe tongue in this direction also pushes or levers portions of thelarynx in the pharyngeal-to-laryngeal direction and thereby tends toprevent the cuff from fitting tightly around the larynx. This weakensthe seal provided by the LMA by decreasing pressure between the cuff andanatomical structures such as the pyriform fossae.

FIG. 15B shows LMA 400 in the fully inserted configuration. The dashedline 1602 represents the contour assumed by the tongue when prior artLMA 1500 is in the fully inserted configuration. As shown, the enlargedempty space S provided by LMA 400 allows the tongue to assume a morenatural position than prior art LMA 1500. In particular, the enlargedempty space S of LMA 400 allows the tongue to be displaced in thelaryngeal-to-pharyngeal direction from where the tongue would be if LMA1500 were in the fully inserted configuration. Allowing the tongue toassume a more natural position also allows other anatomical structuresto assume a more natural position (i.e., to be displaced in thelaryngeal-to-pharyngeal direction from where they would be if LMA 1500were in the fully inserted configuration) and thereby improves the sealprovided by LMA 400.

As is well known, portions of the larynx (e.g., the ariepiglottic folds)can extend into the bowl shaped space bounded by the inflated cuff whenan LMA is in the fully inserted configuration. FIG. 15B suggests this byshowing structures 1530 extending into the bowl-shaped volume defined bythe cuff and backplate of LMA 400. Enlarging the space S also has thebeneficial effect of increasing the size of the bowl-shaped volumedefined by LMA 400 (i.e., increasing the empty space that is bounded bythe backplate portion and the inflated cuff of LMA 400). This alsoimproves the quality of the seal provided by LMA 400 by allowing thelarynx to extend further into the bowl-shaped volume than was possiblewith prior art LMAs. Allowing the larynx to extend further into thisspace allows the larynx to assume a more natural position (i.e., aposition similar to the position the larynx would occupy if the LMA werenot inserted) and improves the seal provided by the LMA.

Several features of LMA 400 cooperate to provide the enlarged emptyspace S. First, as shown in FIG. 5A, the thickness T5 of the proximalportion of the mask portion is substantially thicker than the thicknessT4 of the distal portion of the mask portion. Another feature thatcooperates to define the enlarged empty space S is the angle between thecentral portion 418 and the backplate portion 419 of the airway tube. Asshown in FIG. 4A, at the junction of the central portion 418 and thebackplate portion 419, the central portion 418 extends at an angle alphawith respect to the plate 440. In one preferred embodiment, the anglealpha is equal to ten degrees plus or minus two degrees. Morepreferably, the angle alpha is equal to ten degrees plus or minus onedegree. Even more preferably, the angle alpha is substantially equal toten degrees. This angle provides additional clearance between theproximal end of the plate and the inner side of the airway tube asmeasured in the laryngeal-to-pharyngeal direction. Yet another featurethat contributes to defining the empty space is an absence of aninflation tube in the space. In most prior art LMAs, as shown forexample in FIG. 3, the inflation tube extends from the proximal end ofthe cuff in the distal-to-proximal direction into the space. However, inLMA 400, as shown for example in FIG. 12, the inflation tube does notextend from the proximal end of the cuff and instead extends from thepharyngeal side of the plate to one of the notches 425 without enteringthe space S.

As discussed above, and as illustrated in FIGS. 5A-5C and 15B, onefeature that helps define the enlarged empty space S is the increasedthickness of the proximal end of the inflated cuff. When LMA 400 is inthe fully inserted configuration, the inflatable cuff is preferablyinflated to a pressure of about 60 cm H₂O. The pressure in the cufftends to increase during surgical procedures because commonly usedanesthesia gasses (e.g., nitrous oxide) tend to diffuse through thesemi-permeable cuff wall. One advantage of forming mask portion 430 outof PVC is that a cuff formed of this material can hold the profileillustrated in FIGS. 5A-5C and 15B when the intra-cuff pressure risesdue to this diffusion. In contrast, if the cuff were formed from a moreelastic material, such as the silicone material used to form most priorart LMA cuffs, the cuff would not tend to hold this profile and wouldinstead deform, or “balloon out”, when intra-cuff pressure rises due tothis diffusion.

Yet another advantage of LMA 400 relates to the ease with which it canbe inserted into a patient. FIG. 16A shows a side view of LMA 400 whenthe cuff 460 is deflated. FIGS. 16B and 16C show perspective views ofLMA 400 when the cuff 460 is deflated. The thickness T3 (as shown inFIG. 6) of the cuff is sufficiently thin, that when the cuff 460 isdeflated, the profile of the distal portion of the LMA is almostentirely determined by the plate 440 of the mask portion and thebackplate portion 419 of the airway tube. As shown in FIG. 16A, thethickness T10 of the distal end, as measured in thelaryngeal-to-pharyngeal direction, is virtually entirely determined bythe thickness of the plate 440. The thickness of the deflated LMA, asmeasured in the laryngeal-to-pharyngeal direction, gradually increaseswith increases in the distal-to-proximal direction until the thickestpoint, at the proximal end of the mask portion, is reached which has athickness T11, as measured in the laryngeal-to-pharyngeal direction. Therate of increase in thickness is determined by the angle theta betweenthe plate 440 and the pharyngeal side of backplate portion 418. Inpreferred embodiments, the angle theta is about eleven degrees and thethickness T10 is about two millimeters (i.e., the deflated cuff addsvirtually no thickness beyond the thickness of the plate T2). Thethickness T11 is preferably about seventeen millimeters plus or minustwo millimeters. More preferably, the thickness T11 is about seventeenmillimeters plus or minus one millimeter. Even more preferably, thethickness T11 is substantially equal to seventeen millimeters. Thethickness T11, which is the thickest part of deflated LMA 400 asmeasured in the laryngeal-to-pharyngeal direction, is relatively thin ascompared with prior art LMAs, which are usually about twenty-sixmillimeters thick in comparable sizes.

FIG. 16C illustrates the size of the deflated LMA 400 as measured in theleft-to-right direction. The width of the distal tip of the LMA isrelatively narrow and the width of the LMA gradually increases withincreases in the distal-to-proximal direction. The width of the widestpart of the deflated LMA, as measured in the left-to-right direction, W1is equal to the width of the widest part of the plate (as shown in FIG.5E).

The overall profile of deflated LMA 400, as measured in thelaryngeal-to-pharyngeal direction, as well as the left-to-rightdirection, is small as compared with prior art deflated LMAs. Havingsuch a small profile greatly increases the ease with which deflated LMA400 may be inserted into a patient. In particular, the thin profile, asmeasured in the laryngeal-to-pharyngeal direction, makes it very easy topush the deflated mask portion and backplate between a patient's upperand lower teeth and past the patient's throat. The thin profile alsoincreases the likelihood that the deflated mask portion will fit betweenthe pharyngeal wall and the epiglottis without disturbing or otherwisepushing on the epiglottis as the distal tip of the mask portion is beingpushed past the epiglottis towards the esophageal sphincter.

FIG. 17 shows a deflated LMA 400 that has been partially inserted into apatient that is resting in the neutral position. As shown, the distaltip 434 of the deflated LMA has fit between the patient's pharyngealwall 1078 and the epiglottis 1710. When an unconscious patient lies ontheir back, relaxation of the muscles tends to allow the back of thetongue and the epiglottis to drop down towards the pharyngeal wall,thereby reducing or minimizing the space between the epiglottis and thepharyngeal wall. Accordingly, the thinner the deflated LMA, the morelikely it is that the LMA will fit into the space between the pharyngealwall and the epiglottis without pushing on or otherwise moving theepiglottis. The slim profile of deflated LMA 400 accordingly facilitatesproper insertion of the LMA.

One problem with prior art LMAs is that they are often insertedimproperly. As discussed above, the LMA is a “forgiving” device andtends to establish an airway even when the device is improperlyinserted. However, ideally, the LMA should be inserted properly so thatthe epiglottis is not disturbed and so that the distal tip of the LMA isdisposed adjacent the esophageal sphincter. One problem that contributesto the difficulty of inserting prior art LMAs relates to the profileassumed by the deflated cuff. In prior art LMAs, the deflated cuff formsa “structural component” of the LMA in that (1) a significant portion ofthe profile of a deflated prior art LMA is determined by the cuff and(2) the shape of the deflated cuff significantly affects the path takenby the LMA through the body as it is inserted into a patient.Accordingly, proper insertion of a prior art LMA generally requiresproperly forming, or shaping, the cuff as it is deflated. U.S. Pat. No.5,711,293 discloses an example of a prior art forming tool for formingan LMA into an ideal shape for insertion as the cuff is being deflated.

In LMA 400, the deflated cuff contributes only insignificantly to theprofile of the deflated LMA. Rather, the profile of the deflated deviceis determined almost entirely by the plate 440 of mask portion 430 andthe backplate portion 419 of airway tube 410. As shown in FIG. 16A-C,these components define a slim profile that facilitates proper insertionof the LMA.

Another advantage of LMA 400 relates to the profile of the device whendeflated as compared with the profile of the device when inflated. Asdiscussed above, when LMA 400 is deflated it presents a slim, thin, orsmall profile as compared with prior art LMAs. However, when LMA 400 isinflated, the cuff expands considerably and, as discussed above, thisallows the LMA to provide an improved seal with the tissues surroundingthe patient's glottic opening. The relatively large difference betweenthe thickness (as measured in the laryngeal-to-pharyngeal direction) ofthe deflated device as compared with the thickness of the inflateddevice distinguishes LMA 400 from prior art LMAs. As discussed above,the thickest part of the deflated LMA, T11, is about seventeenmillimeters. The thickest part of the inflated LMA, T5, is about 25.4millimeters. Accordingly, the thickest part of the inflated LMA 400 isapproximately 1.5 times larger than the thickest part of the deflatedLMA 400. Although 1.5 is a preferred factor for distinguishing thethickest parts of the inflated and deflated LMA, it may be preferablefor the thickest part of the inflated LMA to be 1.5, plus or minus 0.15,times larger than the thickest part of the deflated LMA (i.e.,T5=(1.5±0.15)·T11).

As shown in FIG. 17, any LMA will bend or flex as the LMA is beinginserted into a patient. More specifically, as the distal tip of the LMAcontacts the patient's palato-pharyngeal arch, the distal tip bends downtowards the larynx (or bends about an axis that extends in the left toright direction). As the LMA is inserted further into the patient, theportion of the LMA that is proximal to the palato-pharyngeal arch willbend around the arch and portions of the LMA that have already passed bythe palato-pharyngeal arch will straighten out. In this manner, thepoint of bending or flexing begins at the LMA's distal tip and movesbackwards in the distal-to-proximal direction as the LMA continues to beinserted into the patient.

As shown for example in FIG. 16B, the backplate portion 419 of LMA 400is “spear shaped” or tapered in that its width decreases with increasesin the proximal-to-distal direction. The very narrow width of thebackplate's distal tip makes the LMA's distal tip relatively flexible sothat the distal tip easily bends or flexes downwards towards the larynxas the LMA 400 is inserted into the patient. As the LMA is insertedfurther, and the LMA's resistance to bending increases in a linearfashion due to the gradual widening of the “spear shaped” backplateportion. This linear increase in resistance to bending about an axisthat extends in the left-to-right direction is an advantageous featureof LMA 400. If the increase in resistance were not linear and insteadincreased suddenly or dramatically (in a non-linear fashion) at one ormore points as the LMA was being inserted, the LMA would tend to kink,or form a localized fold, instead of bending smoothly around thepalato-pharyngeal arch. Such a kink-like deformation would be morestimulating to the patient and increase the likelihood of malpositionand/or trauma during insertion. Some prior art LMAs are capable ofoffering a substantially linear increase in resistance to bending as theLMA is inserted into a patient as long as the cuff has been properlydeflated and formed into a proper configuration. However, since the cuffof these prior art LMAs forms a structural component of the LMA, they donot offer a linear increase in resistance to bending, and tend to formkinks while being inserted, when the cuff is deflated without proper useof a forming tool. One advantage of LMA 400 is that the LMA will providethe desired substantially linear increase in resistance to bendingregardless of the manner in which the cuff is deflated. This is sobecause the deflated cuff does not contribute significantly to thestructure of the LMA and the LMA's resistance to bending is virtuallyentirely determined by the geometry of the backplate portion 419.

Yet another advantage of LMA 400 relates to the size of the inflatedcuff. As shown for example in FIGS. 5A and 15A, the thickness T5, asmeasured in the pharyngeal-to-laryngeal direction, of the proximal endof the inflated cuff is relatively large as compared with prior artLMAs. The relatively large thickness T5 of the proximal end of theinflated cuff advantageously increases the separation between theepiglottis and the aperture 442 of plate 440 and thereby decreases thelikelihood that the epiglottis can block the airway provided by the LMA400. Prior art LMAs often included “bars” or “slits” disposed in themask portion to prevent the epiglottis from blocking the airway of theLMA. Such bars are disclosed for example in U.S. Pat. No. 5,297,547 (seeFIG. 8 of the '547 patent). Although LMAs constructed according to theinvention could include such “bars”, LMA 400 advantageously eliminatesthe need for such bars and accordingly may be manufactured lessexpensively.

Returning to FIG. 17, as shown the distal tip of LMA 400 has passedthrough the gap between the epiglottis and the pharyngeal wall.Sometimes the distal tip of the LMA will catch on the epiglottis as theLMA is being inserted and will push the epiglottis into a “down folded”condition. In such a “down folded” condition, the epiglottis may blockthe trachea or the airway provided by an LMA. Another advantage of LMA400 is that the cuff 460 can lift a down folded, or posterior lying,epiglottis forwards, or anteriorly, thereby keeping the airway clear.FIG. 7B illustrates a preferred folded configuration for the deflatedcuff. As shown, when the cuff 460 is deflated, the extra or loosematerial of the cuff may be folded towards the center of the maskportion so that the deflated cuff covers the entire, or nearly theentire, central aperture 442 of plate 440. If the cuff is folded intothis position so that it covers the entire, or nearly the entire,central aperture 442, then the cuff 460 will advantageously lift theepiglottis anteriorly and thereby open the airway as the cuff isinflated.

One disadvantage of prior art re-usable LMAs is that after everysterilization, the cuff must be deflated and the LMA must be configuredfor insertion into a patient. Unfortunately, most physicians who useLMAs lack the skill or dedication required to pack the LMA into theoptimal configuration for facilitating insertion. Another advantage ofLMA 400 is that when it is used as a disposable device, the LMA may bepackaged and sold in a configuration that is optimal for facilitatinginsertion of the device into a patient. As discussed above, LMA 400 isadvantageous because (1) the deflated cuff only adds a small amount ofthickness to the mask portion and (2) the deflated cuff may beconfigured for lifting a down folded or posterior lying epiglottis outof the way. Preferably, the LMA 400 is placed into this optimalconfiguration (i.e., with the cuff deflated and folded as discussedabove in connection with FIGS. 7A and 7B) prior to sale and thenpackaged into a sterile bag or package (e.g., a sterile plastic bag).So, when a physician wishes to insert an LMA into a patient, thephysician may simply remove an LMA from its sterile packaging and insertit into the patient without having to first deflate or reposition thecuff.

As discussed above, in some embodiments of LMA 400 an inflation tube 490need not be provided. So, in embodiments that do not include inflationtubes, fabrication of the LMA is completed by attaching the airway tubeto the partially inflated mask portion after the mask portion is removedfrom the mold. When mask portion 430 is formed by rotational molding,the cuff is partially inflated when the mask portion is removed from themold. The amount of air that is trapped in the cuff during fabricationis similar to the amount of air that is normally injected into the cuffvia the inflation tube after the mask portion has been inserted into apatient to achieve the desired intra-cuff pressure of 60 cm H₂O.Accordingly, such a partially inflated cuff is capable of forming aneffective seal around a patient's laryngeal inlet.

These masks have one principal disadvantage as compared with embodimentsof LMA 400 that do include an inflation tube. The profile of thepartially inflated cuff is thicker, as measured in theproximal-to-distal direction, than is achievable in LMA 400 when thecuff is fully deflated via the inflation tube, and this can makeinserting the LMA more difficult. However, LMAs that do not include aninflation tube do have one principal advantage. Namely, they can beeasier and faster to use in emergency situations because thepractitioner need not bother with deflating or inflating the cuff, andthe airway is established as soon as the mask portion is inserted intothe patient's pharynx. The thicker profile can complicate insertion ofsuch an LMA. However, two factors make the insertion easier than mightotherwise be the case. First, in unconscious patients, the muscles ofthe body become very relaxed which can make it easier to push a thickprofile device through the upper and lower teeth and down the throat.Second, since the cuff is only partially inflated, and since the cuff isvery thin and flexible, a very small amount of pressure applied to oneportion of the cuff will squeeze, or shrink the size of that portion,and force air trapped in the cuff into other portions of the cuffthereby inflating or expanding those other portions. For example, theproximal end of the cuff will expand if the distal end is squeezed flat,and only a very small pressure is required to squeeze the distal endinto a flat shape. As an LMA 400 with a partially inflated cuff isinserted into a patient, some parts of the cuff may expand while otherparts are squeezed by anatomical structures. However, the ability toshrink in some places while expanding in others makes it relatively easyto push the partially inflated cuff into the patient's pharynx.

Accordingly, one method of making an LMA according to the invention isto (1) produce mask portion 430 using the rotational molding processdescribed above in connection with FIGS. 8A-8D; (2) remove mask portion430 from the mold 800; and (3) attach an airway tube to the maskportion. The rotational molding process produces a partially inflatedmask portion that is inflated to a suitable degree. Once the airway tubeis attached to the mask portion, fabrication of the LMA is complete. Aninflation tube need not be added. The completed LMA may be packaged forsale in a sterile bag. Such LMAs may be very useful for emergencysituations, for example for use by emergency workers in ambulances oremergency wards.

FIG. 18A shows a side view of another embodiment of an LMA 1800constructed according to the invention. FIGS. 18B and 18C show twoperspective views of LMA 1800. As shown, LMA 1800 is very similar to LMA400. Both LMA 1800 and LMA 400 include identical mask portions 430.Also, the backplate of both LMAs 1800 and 400 are very similar. Theprincipal difference between the two LMAs is in the airway tube.

The airway tube 1810 of LMA 1800 is a double barreled tube. FIG. 18Dshows a sectional view of airway tube 1810 taken in the directionindicated by line 18D—18D as shown in FIG. 18A. Airway tube 1810includes a left tube 1812 and a right tube 1814. The tubes are fixed,bonded, or extruded together at a central joint 1816 that extends fromthe proximal ends to the distal ends of the two tubes. Airway tube 1810also defines an inner side 1810-i and an outer side 1810-o.

As with airway tube 410, tube 1810 has an overall oblong or flattenedcross section. Accordingly, tube 1810 (like tube 410), fits relativelywell within the patient's anatomical airway and minimizes theintra-dental gap required to accommodate the tube. Also as with tube410, airway tube 1810 includes a proximal portion 1820, a centralportion 1822, and a backplate portion 1824. Backplate portion 1824 isalmost identical to backplate portion 419. The only principal differencebetween the two backplate portions is how they couple to theirrespective central portions of the airway tube.

As shown in FIG. 18D, the junction of the two cylindrical tubes 1812 and1814 at the joint 1816 forms two grooves, or recesses, 1830, 1832 in theairway tube. The groove 1830 extends along the inner side 1810-i of theairway tube and the groove 1832 extends along the outer side 1810-o ofthe tube. One advantage of tube 1810 is that the groove 1830 can serveas a guide for guiding subsequently inserted tubes, such as for examplean endotracheal tube. That is, after LMA 1800 has been positioned in thefully inserted configuration, the groove 1830 can be used to guide asubsequently inserted device. FIG. 19A shows a perspective view of anendotracheal tube being guided by groove 1830 as the endotracheal tubeis inserted into the patient's body (not shown).

Embodiments of LMA 1800 that are used to guide a subsequently insertedendotracheal tube (or some other kind of tube), preferably define a“gap”, or aperture, between the mask portion and the backplate portionat the proximal end of the mask portion. When the distal tip of theendotracheal tube reaches the mask portion's proximal end, continuedinsertion of the endotracheal tube will push the endotracheal tube'sdistal end through the gap between the mask portion and the backplate ofthe LMA and enable the endotracheal tube's distal end to proceed throughthe aperture 442 of the mask portion and into the patient's trachea.

FIG. 19B shows an embodiment of LMA 1800 that defines such a gap 1910.Both LMA 400 and LMA 1800 are constructed by attaching or bonding theouter perimeter of the laryngeal side of the backplate portion of theairway tube to the pharyngeal side of the plate 440 of the mask portion430. In the case of LMA 400, the entire outer perimeter of the backplateportion is so attached to the plate 440. However, in the case of LMA1800, one portion of the outer perimeter of the backplate (at thebackplate's proximal end) is not bonded to the plate 440 and the rest ofthe outer perimeter of the backplate is bonded to the plate 440. Sincethe proximal ends of the backplate and plate 440 are not bondedtogether, pressure on the plate 440 can push the plate 440 of the maskportion away from the backplate and create the gap 1910. In the absenceof downward pressure on the plate 440, the portions of the backplate andplate 440 that are bonded together tend to hold the unbonded portionstogether as well. The effect is to create an LMA that has a “flapvalve”. Under normal conditions, the plate 440 and backplate of LMA 1800remain in contact as in the case of LMA 400. Also, when LMA 1800 is inthe fully inserted configuration, pressure exerted by the patient'spharyngeal and laryngeal walls tends to push the plate 440 and backplatetowards one another, or together. However, in LMA 1800, pressure on theproximal end of the mask portion (generated for example by subsequentinsertion of an endotracheal tube that is guided by groove 1830) canpush the plate 440 away from the backplate to generate the gap 1910.Subsequently inserted endotracheal tubes can extend through gap 1910 andthen through aperture 442 and into the patient's trachea.

FIG. 20 shows a perspective view of an alternative embodiment of a maskportion 430′ that may be used in LMA's constructed according to theinvention. Mask portion 430′ is similar to mask portion 430, however,the pharyngeal side of the plate 440′ of mask portion 430′ is not flatand instead defines a step, or recess, 2010, that extends around theelliptical central aperture of the mask portion. It will be appreciatedthat the recess 2010 may be used to properly locate the backplateportion of the airway tube when the backplate portion is fixed to themask portion. Preferably, the laryngeal side of the backplate portion isbonded or fixed to the bottom of the recess 2010. When the backplateportion is fixed to the bottom of recess 2010, a small portion 2012 atthe distal end of the plate 440′ separates the distal tip of thebackplate portion from the distal tip of the LMA. This may beadvantageous because the airway tube is generally harder and stifferthan the mask portion. So, as the LMA is inserted into a patient, andthe LMA's distal tip contacts anatomical structures within the patient'snatural airway, the contact is between the patient and the relativelysoft mask portion rather than between the patient and the harderbackplate portion. Mask portion 430′ thereby advantageously provides asimple mechanism for properly locating the backplate portion when theLMA is being assembled and also protects the patient from potentialtraumatic contact with the relatively hard distal tip of the backplateportion as the LMA is being inserted. It will be appreciated that maskportion 430′ may be used in place of mask portion 430 in LMA 400, LMA1800, or any other LMAs constructed according to the invention.

As discussed above in connection with FIGS. 10B and 10C, thelongitudinal folds in the airway tube permit the tube to compresssomewhat in a concertina or accordion like fashion. Another advantage ofthe longitudinal folds is that they can permit the airway tube to expandin response to forces applied to the interior of the tube. Thisexpansion can advantageously permit the airway tube to accommodate asubsequently inserted endotracheal tube and thereby allows LMA 400 tofunction as an intubating LMA. FIG. 10D shows a side view of anembodiment of LMA 400 into which an endotracheal tube 1010 has beeninserted. To reach the configuration illustrated in FIG. 10D, the distalend 1012 of endotracheal tube 1010 was inserted into the proximal end ofintegral tube and backplate section 416 and advanced through the section416 until the distal end 1012 emerged through the aperture in the maskportion 430 as shown. As the endotracheal tube 1010 advances throughintegral tube and backplate section 416, the longitudinal folds in thesection 416 allow the section 416 to expand and thereby accommodate theendotracheal tube.

It will be appreciated that when LMA 400 is used as an intubating LMA,it may be desirable to use alternative embodiments of the airway tube410 or the integral tube and backplate section 416. For example, theintegral tube and backplate section 416 shown in FIG. 10D includes twolongitudinal folds that extend down the left and right sides of the tuberather than the single fold provided in the section 416 illustrated inFIGS. 10B and 10C. FIG. 10E shows a cross section of the section 416taken in the direction of line 10E—10E as shown in FIG. 10D. FIG. 10Eshows the two longitudinal folds that extend down the left and rightsides of the integral tube and backplate section. FIG. 10E shows theintegral tube and backplate section in an expanded condition. That is,the longitudinal folds have expanded in a concertina like fashion toaccommodate the subsequently inserted endotracheal tube. It will beappreciated that airway tubes constructed according to the invention maybe provided with one, two, or more longitudinal folds that extend downthe left and right sides of the tube.

In addition to including extra longitudinal folds, it will beappreciated that it may be advantageous for the airway tube, or integraltube and backplate section, of intubating LMAs constructed according tothe invention to include a modified proximal end that is cylindrical orotherwise wide enough to accommodate insertion of an endotracheal tubeas shown in FIG. 10D.

FIG. 10F shows a side view of another embodiment of LMA 400 constructedaccording to the invention, and FIG. 10G shows a perspective view of theembodiment shown in FIG. 10F. In the illustrated embodiment, the airwaytube includes a ridge 1020. Ridge 1020 extends in the proximal-to-distaldirection from a point near the middle of the backplate portion 419 to apoint in the curved portion 418 that is proximal to a junction of thebackplate portion 419 and the curved portion 418. Ridge 1020 alsoextends from the outer side of the tube 410-o into the interior of thepassage defined by the tube. In this embodiment, the walls of the tubenear the junction of the curved portion 418 and the backplate portion419 are also preferably weaker than the walls in other portions of thetube. For example, the tube wall can be made thinner in this region toweaken this portion of the tube.

The embodiment illustrated in FIGS. 10F and 10G facilitates rotating thepatient's head while the LMA is in the fully inserted configuration. Forexample, the LMA may be placed in the fully inserted configuration whilethe patient is resting in the neutral position (i.e., the patient willbe lying on their back and the patient's nose will be the part of thepatient's head that is furthest from the ground). Once the LMA is solocated, it may be desirable to rotate the patient's head. For example,if the patient's ear is being operated on, it may be desirable to rotatethe patient's head approximately ninety degrees so that instead of thepatient's nose, the patient's ear is now the part of the patient's headthat is furthest from the ground. It will be appreciated that thisexposes the ear and makes it easier to operate on the ear. Ideally,rotating the patient's head in this manner while the LMA is located inthe fully inserted configuration (1) will not disturb the seal betweenthe inflated cuff and the tissues surrounding the patient's glotticopening and (2) will not cause a collapse of the internal passageprovided by the airway tube. Weakening the walls of the airway tube nearthe junction of the backplate portion 419 and the curved portion 418allows the distal part of the LMA (i.e., the mask portion and thebackplate portion) to rotate with respect to the remainder of the airwaytube without placing undue force on the inflated cuff, and this tends topreserve the seal between the cuff and the tissues surrounding theglottic opening when the patient's head is so rotated. Ridge 1020 tendsto prevent the internal passage provided by the airway tube fromcollapsing when the patient's head is so rotated and the airway tube iscorrespondingly twisted.

FIGS. 21 and 22 show another embodiment of an LMA constructed accordingto the invention. In this embodiment, an air inlet tube 10 will beunderstood to provide air (or other gas) service to a patient's lungsvia mask structure 11 and the patient's trachea. As best seen in FIG.22, base structure of the mask 11 comprises a relatively stiffly pliantskeletal base 12 of generally elliptical configuration, a portion ofthis base being viewable directly through a draftsman's break through acollapsed thin-film inflatable envelope 13, which will be understood tobe inflatable by external supply of inflation air via a flexibleinflation line 15; line 15 will be understood to include a conventionaltwo-way check valve (not shown) for purposes of holding an inflatedcondition of the envelope 13 (as in FIG. 21) or for holding a deflatedcondition of the envelope (as in FIG. 22). The envelope 13 is merely aninflatable portion of a single-part, integrally formed, total enclosureserved by the inflation/deflation line 15, being the product of aso-called rotational-molding process, wherein a single plastic materialin liquid state is caused to progressively build a thin layer or film ofcured plastic material against and throughout the internal surface areaof a given annular mould cavity, the gravitationally drained remained ofthe liquid-phase plastic being allowed to cure in situ as the relativelystiff skeletal annular member of the LMA, at the bottom of the mould.The cured product of such moulding not only provides the indicatedskeletal-base function but also, between the inner and outer peripheriesof the skeletal annulus provides the additional function of completing,as a skeletal annulus, the inflatable and peripherally yieldableenclosure of envelope provided by the moulded film. For the case of thedescribed integrally formed component (12/13) when formed of suitableplastic such as polyvinylchloride, the thin film at 13 is typically ofthickness in the order of 0.1 to 0.3 mm, while the skeletal base 12 maybe typically 10 to 20 times the moulded thickness of the film 13. Suchfilm will be understood to collapse and flatter or mat itself at randomin response to deflation action via line 15. It is to be understood thatwhile it is possible to form the skeletal base 12 as flat and ofrelatively uniform thickness, it is also possible to use the describedmoulding process to develop a skeletal-base thickness which varies as afunction of longitudinal progression, as from a relatively thickproximal location (e.g., 2-3 mm thick) to a much reduced distal-endthickness (e.g., 1-mm), thereby according a desired distal-endbendability which can usefully serve the process of installing the LMAin the patient. Such a proximal-to-distal thickness variation is laterindicated in FIG. 25 (at 12′) as a feature of the device of FIGS. 23 and24.

To complete a description of the LMA device of FIGS. 21 and 22, theairway tube 10 is shown to be supported on and by its overlap withposterior surface of the proximal region of the annulus of skeletal base12, the distally open end 16 of the airway tube having preferably anangularly truncated configuration, which is open within the generallyelliptical lumen 17 of the skeletal base 12. Finally, closure of theposterior side of the mask structure is effected by a tent-like roof 18of flexible plastic sheet material, wherein the lapped distal portion ofthe airway tube is analogous to a ridge pole, so that the tent-like roofsheeting slopes away from its longitudinally central support by thedistal end of the airway tube, to its peripherally sealed engagement tothe rim of the skeletal base, as seen in FIG. 21, it being understoodthat sheeting 18 is also suitably draped and sealed at its proximal-endclosure around the airway tube 10.

FIGS. 23 and 24 are recognizable for their resemblance to FIGS. 21 and22, except for the additional provision of a gastric-drainage tube 20,in side-by-side bonded relation to an airway tube 21, which may in allrespects be as described for airway tube 10 of FIGS. 21 and 22, exceptfor the fact that tubes 20/21 are symmetrically and oppositely offsetfrom the longitudinal sagittal plane of the generally ellipticalconfiguration of mask structure 22. This symmetrical relation is seen tocontinue until the distally open end 23 of the airway tube 21 ispositioned to vent over the lumen 24 of the generally elliptical annularskeletal base 25 of the mask structure. As with the LMA of FIGS. 21 and22, the base skeletal member 25 may be a product of a rotationalmoulding operation wherein a thin-film inflatable/deflatable annularenvelope 26 is integrally formed therewith, with provision for selectiveinflation/deflation action via a flexible line 15, as also in FIGS. 21and 22.

For gastric-drainage purposes, and as better seen in FIGS. 25 to 29, thedrainage tube 20 is seen in FIG. 26 to undergo a mild zig-zag coursechange, from lateral offset adjacency to airway tube 21 to itsdistal-end alignment of symmetry with respect to the sagittal plane ofthe mask. Within the distal half of the skeletal base 25, and the distalend of drainage tube 20 passes through the base 25 and projects itsangularly truncated open end 27 slightly beyond the distal end of base25.

As previously noted, the longitudinal progression of reducing thicknessof skeletal base 25 in the distal direction enables a more pliant actionto be inherently imparted to the distal half of the mask. FIG. 25 alsoillustrates that the inflated sectional area of the inflated thin-filmenvelope 26 is similarly and progressively decreased in the distaldirection, so that tubes 20, 21 may be oriented at proximal departurefrom the mask to incorporate a preferred angle α in the range 20° to30°, at commencement of their proximal course over the tongue, for air(gas) and gastric servicing connections (not shown), as necessaryoutside the patient's mouth.

As with the LMA of FIGS. 21 and 22, the structure of FIGS. 23 and 24 maybe completed with a tent-like closure 28 of the posterior side of themask. Again, such closure is realized by pliant sheet material which inFIG. 28 is seen to derive “ridge-pole” support from tube 20, centered onthe distal-half of skeletal base 25. In FIG. 29, the section shows thetent closure 28 to be supported over the adjacent tubes 20, 21 atpassage over the lumen 24 of the mask, with the skirt of tent sheetingperipherally secured to skeletal base 25, it being again understood thatat its proximal end, the tent sheeting is also conformed and sealed toboth tubes 20, 21 to complete closure of the posterior side of the mask.

In FIG. 28, a bulging profile in phantom outline 30 on the anterior sideof the mask will be understood to suggest film-envelope inflation awayfrom the anterior surface of skeletal base 25, and a further inflationprofile 31 in phantom outline on the posterior surface of the mask willbe understood to suggest an inflatable cuff 31 over the periphery ofbase 25, to provide cushioned reference of the mask to the back wall ofthe patient's pharynx. As shown, the back-cushion material is shown forits further connection to tent 28 along the sagittal-plane interceptwith tent 28.

It is desired that for ease of installation of the mask in a patient,that the deflated condition should offer a minimum thickness dimension.this will be clear from FIGS. 28 and 29 where the respective minimumdimensions D1, D2 are to be compared with maximum available inflationdimensions D3, D4 without the back cushion 31, and D5, D6 with the backcushion 31.

In the embodiment of FIGS. 30 to 32, the simplest difference to note isthat the skeletal base 40 is flat and its integrally formed thin-filminflatable envelope portion 41 is otherwise as described for theinflatable film 26 of FIG. 25. Also, the distal portion 42 of thedrainage tube 43 is locally bent for straight but inclined passagethrough a similarly inclined orienting opening 44 in the distal-endregion of base 40. At remaining overlap with the proximal-end region ofbase 40, the drainage tube 43 is laterally offset to the extent that itcan symmetrically pair with airway tube 44, and both tubes 43, 44 can bebonded to the supporting flat posterior surface of base 40. Tentlikesheet material described for closure of the posterior side of the maskcan be as described for FIGS. 25 to 29, it being noted that at sectiona—a of FIG. 30, the local section bears an almost identically similarappearance to that depicted in FIG. 28 for the mask of FIG. 27.

According to one technique of manufacture of the unitary base 40 withintegrally moulded thin-film envelope portion 41, this single componentis depicted in the longitudinal section of FIG. 21 and in the plan viewof FIG. 22, it being understood that such passages as at 43′ (fordrainage-tube passage as at 43′, for drainage-tube orientation), at 45(for inflation-air access), and at 46 (for lumen definition) are theproduct of known core-pin and other mould-feature defining structures ofthe mould as an entirety. The preassembly of tubes 43,44 in side-by-sideadjacency, together with the pre-bent and truncated open distal end ofdrainage tube 43 are later assembled for adhesively or otherwise sealedpassage of the distal end of the drainage tube 43 and for film-piercedand peripherally sealed passage of the truncated distal end of tube 43into the relationship depicted in FIG. 30.

In an alternative mode of structural assembly, depicted in FIG. 31A, apreformed and suitably bent distal-end fitting 50, for later assembly tothe remainder of the drainage tube (not shown) is an insert part whichin the process of rotation-moulding becomes the FIG. 31A part to belater assembled to mask parts that become an LMA with thegastric-drainage feature. To this end, the preassembled drainage andairway tubes 43, 44 will be understood to terminate over the lumen 46and that the distally projecting end of the drainage-tube portion (43)of this tube (43, 44) preassembly may be suitably fitted to the openproximal end of fitting 50, to establish continuity of the fulldrainage-tube function. Such continuity may be provided by knowntechniques of telescoping fit, as to the extent denoted by dotted line51 in FIG. 31A, or by a short sleeve of heat-shrink plastic material(not shown) which laps the abutting ends of equal diameter tubular ends,namely the proximal end of fitting 50 to the distal end of the two-tubepreassembly (43, 44).

The plan view of skeletal base 40′ of FIG. 33 will be recognized asidentical to that of FIG. 32, except that two spaced elongate parallelbars 55, 56 Symmetrically straddle the longitudinal sagittal plane ofthe mask (not shown) into which this component can be integrated. Thepurpose served by bars 55, 56 is to provide a measure of support for thedrainage tube 43 as it passes over the lumen and as it alters course fordistal-end symmetrical orientation with respect to the sagittal plane.

Since certain changes may be made in the above apparatus withoutdeparting from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown inthe accompanying drawing shall be interpreted in an illustrative and nota limiting sense.

What is claimed is:
 1. A laryngeal mask airway device, comprising a maskportion and an airway tube, the airway tube extending from a proximalend to a distal end, the distal end of the airway tube being fixed tothe mask portion, the mask portion being insertable through the mouth ofa patient to an inserted location within the patient, the mask portionforming a seal around the patient's glottic opening when the maskportion is in the inserted location, the proximal end of the airway tubebeing disposed outside of the patient when the mask portion is in theinserted location, the airway tube having a left side, a right side, aninner side, and an outer side, a distance between the left and rightsides being greater than a distance between the inner and outer sides,the tube having a longitudinal fold extending along the left side and alongitudinal fold extending along the right side, the longitudinal foldsdefining grooves that extend along the left and right sides of anexterior of the tube.
 2. A device according to claim 1, furtherincluding an inflation tube coupled to the mask portion for selectivelyinflating part of the mask portion, a portion of the inflation tubebeing disposed in one of the grooves.
 3. A laryngeal mask airway deviceincluding a mask portion and an airway tube, the mask portion includinga generally elliptical plate and a cuff, the elliptical plate defining alaryngeal side, a pharyngeal side, and a central aperture, an innerperimeter of the cuff being attached to the laryngeal side of the plateproximal to a perimeter of the aperture, an outer perimeter of the cuffbeing attached to the laryngeal side of the plate proximal to an outerperimeter of the plate, the airway tube extending from a proximal end toa distal end, the distal end of the airway tube being attached to thepharyngeal side of the plate, a distance between the pharyngeal side ofthe plate and the laryngeal side of the plate being two millimeters plusor minus 0.2 millimeters, a thickness of the cuff wall being 0.14millimeters plus or minus 0.006 millimeters.
 4. A laryngeal mask airwaydevice including a mask portion and an airway tube, the mask portionincluding a generally elliptical plate and a cuff, the elliptical platedefining a laryngeal side, a pharyngeal side, and a central aperture, aninner perimeter of the cuff being attached to the laryngeal side of theplate proximal to a perimeter of the aperture, an outer perimeter of thecuff being attached to the laryngeal side of the plate proximal to anouter perimeter of the plate, the pharyngeal side of the plate defininga recess that extends around the aperture, the airway tube extendingfrom a proximal end to a distal end, the distal end of the airway tubeextending into the recess and being attached to the pharyngeal side ofthe plate.
 5. A laryngeal mask airway device including a mask portionand an airway tube, the mask portion including a generally ellipticalplate and a cuff, the elliptical plate defining a laryngeal side, apharyngeal side, and a central aperture, an inner perimeter of the cuffbeing attached to the laryngeal side of the plate proximal to aperimeter of the aperture, an outer perimeter of the cuff being attachedto the laryngeal side of the plate proximal to an outer perimeter of theplate, the mask portion extending from a proximal end to a distal end,the airway tube extending from a proximal end to a distal end, an outerperimeter of the airway tube's distal end including a first portion anda second portion, the first portion of the perimeter being attached tothe pharyngeal side of the plate, the second portion of the perimeternot being attached to the mask portion, the second portion of theperimeter being disposed near the proximal end of the mask portion.
 6. Alaryngeal mask airway device, comprising a mask portion and an airwaytube, the airway tube extending from a proximal end to a distal end, thedistal end of the airway tube being fixed to the mask portion, the maskportion being insertable through the mouth of a patient to an insertedlocation near the patient's glottic opening, the airway tube having aleft side and a right side, the tube defining a groove that extendsalong the left side of an exterior of the tube, the tube defining agroove that extends along the right side of the exterior of the tube. 7.A device according to claim 6, the tube defining an inner side and anouter side, a distance between the left and right sides being greaterthan a distance between the inner and outer sides.
 8. A device accordingto claim 6, the mask portion forming a seal around the patient's glotticopening when the mask portion is in the inserted location.
 9. A deviceaccording to claim 6, the mask portion including an inflatable cuff, thecuff forming a seal around the patient's glottic opening when the maskportion is in the inserted location and when the cuff is inflated.
 10. Adevice according to claim 6, the tube having a longitudinal foldextending along the left side and a longitudinal fold extending alongthe right side.
 11. A device according to claim 10, the longitudinalfolds defining the grooves.
 12. A device according to claim 11, thelongitudinal folds further defining bulges that extend towards aninterior of the tube.
 13. A device according to claim 6, the airway tubebeing characterized by a durometer of seventy plus or minus fifteenShore A.
 14. A device according to claim 6, the tube including abackplate portion, the backplate portion of the tube being attached tothe mask portion.
 15. A laryngeal mask airway device, comprising a maskportion and an airway tube, the airway tube extending from a proximalend to a distal end, the distal end of the airway tube being fixed tothe mask portion, the mask portion being insertable through the mouth ofa patient to an inserted location near the patient's glottic opening,the airway tube having a left side and a right side, the tube defining alongitudinal fold that extends along the left side, the tube defining alongitudinal fold that extends along the right side.
 16. A deviceaccording to claim 15, each of the longitudinal folds defining a groovethat extends along an exterior of the tube and a bulge that extendsalong an interior of the tube.
 17. A device according to claim 16, thetube defining an inner side and an outer side, a distance between theleft and right sides being greater than a distance between the inner andouter sides.
 18. A device according to claim 16, the mask portioncomprising an inflatable cuff.
 19. A device according to claim 18, thecuff forming a seal around the patient's glottic opening when the maskportion is in the inserted location and the cuff is inflated.
 20. Adevice according to claim 19, the airway tube being characterized by adurometer of seventy plus or minus fifteen Shore A.
 21. A deviceaccording to claim 19, the tube including a backplate portion, thebackplate portion of the tube being attached to the mask portion.
 22. Alaryngeal mask airway device, comprising a mask portion and an airwaytube, the airway tube extending from a proximal end to a distal end, thedistal end of the airway tube being fixed to the mask portion, the maskportion being insertable through the mouth of a patient to an insertedlocation near the patient's glottic opening, the airway tube having aleft side and a right side, the tube defining a groove that extendsalong the left side of the tube, the tube defining a groove that extendsalong the right side of the tube, the tube defining a bulge proximal tothe left side that extends towards an interior of the tube and along theleft side, the tube defining a bulge proximal to the right side thatextends towards an interior of the tube and along the right side.
 23. Adevice according to claim 1, the longitudinal folds further definingbulges that extend towards an interior of the tube.